Hello everyone, welcome back to a new video.
In today's video, we are going to discuss the topic of
boats and streams.
This topic will be under time and distance only.
In last class, we had discussed questions related to trains.
Similarly, in this video also we are discussing about time
and distance only.
But, there is one more sub-case, that is boat and stream
case.
So, in case of boat and stream, I will tell you the
terminologies that you should know.
After that, we will discuss questions related to boats.
First of all, everyone should know what is a boat.
Let us assume that this is a paper boat.
So, let us assume that this is a boat.
What is a stream?
You can call any river, lake or body of water as a stream.
So, what is a stream?
Similarly, a man is swimming in a river.
So, the case of a man is related to the case of a stream.
Now, let us understand the case of a boat.
Let us suppose that this is our boat.
And, this is our stream flowing in this direction.
Let us suppose that this is the direction of this stream.
In this direction, our water is flowing.
And, what is a boat?
In which direction a boat can swim?
Either it can swim in this direction or it can row in this
direction.
It has only two cases to row.
Either the boatsman will row in the front or in the back.
If I tell you in terms of boat and stream, either it will
flow in the direction of the stream.
It means that the direction in which our river is flowing,
the boat will also row in that direction.
This is one case.
Now, let us see the first case.
Case 1
When the direction of our boat and stream are same.
Boat and stream have the same direction.
I have written this in short form.
It means that the flow of the stream is also in the same
direction.
Similarly, the boat is also going in the same direction.
So, what will be the case in this?
Obviously, all of you must have done boating.
You must have rowed a boat in the rainwater in your
childhood.
So, what happens in that?
The direction in which our flow of water is going, if the
boat also goes in the same direction, it will move faster.
It will reach faster.
It will get ready faster.
And if we do the opposite of that, then it will be
difficult for us.
Obviously, if our river is flowing in the opposite
direction, then we need more strength to take the boat,
rather than to take it in the same direction.
So, what will we use in this?
For example, we had a case of two moving bodies.
When we had a case of two moving bodies, like a train and
another train, then what did we use?
We used the concept of relative speed.
Similarly, in this case also, we will not take the normal
speed.
We will see a different speed.
How will we find that?
We will find that in all these cases.
In which case we will take which speed?
So, let us see our first case.
When we have both in the same direction.
So, please write case 1.
Will it be clear to you?
I did not tell you the terminology, which I should have
told you.
If the boat is going in the same direction of the river
flow, then in that case, what will we call it?
We will call it upstream.
Sorry, not upstream, downstream.
This is downstream.
And when it will go in the opposite direction, that the
river flow is going in this direction, but now, our boat is
moving in the opposite direction.
If the boat is moving in this direction, then in that case,
what will we have?
In that case, we will have upstream.
So, you should be clear about two terms.
One is upstream and the other is downstream.
Downstream, when the boat is moving in the same direction
of the river flow.
And the second case is upstream, when the boat is moving in
the opposite direction.
In which opposite direction?
The boat is moving in the opposite direction of the river
flow.
So, we will do both these cases.
And we will also see what will be our speed in these cases.
So, first case.
Case 1.
Upstream case 2.
Downstream.
So, downstream and upstream, you can write in the bracket,
that river, stream and boat are flowing in same direction.
Same direction.
That is downstream case.
And when stream, boat flowing in, flowing will be used for
stream, but for boat it will be rowing.
But I am writing in general, are flowing in opposite
direction.
That would be the case of upstream.
So, what will be the speed in this?
Obviously, when our downstream is moving, means river is
moving with the flow, then what will be our speed?
Speed.
You see, the speed of the boat will be different.
The boat we are drawing, we are drawing the speed of
downstream.
And what were the cases in this?
In this, you tell once, that what all things are moving
with us. Like when our train was moving, then we had the
speed of the train.
When a man is walking, then there is the speed of man,
speed of cycle, speed of scooter.
In this, what all things are moving with us?
In this, our stream, water body is also moving.
So, one will be the speed of our water body.
And one, our boat is also moving.
So, one will be the speed of our boat.
So, how much speed do we have? Two speeds.
So, I will write that for you.
Let us suppose, what will be ours? One, our water stream is
flowing.
So, it should have a speed.
So, one will be the speed of water body or stream.
What should be its speed?
Let us suppose, its speed is y km per hour.
y km per hour.
And second, whose speed will we know?
Speed of boat.
The boat will also have a particular speed.
If it is an electric boat, then it will have a different
speed.
That means, that speed, when you keep it in still water,
means, when there is no speed of water, then, in that case,
what is the general speed of the boat?
What is the normal speed?
We will call that, speed of the boat in still water.
Still means, still water.
What will be the speed of the boat in still water?
Means, speed of the boat will come from that.
Speed of our water body, will not influence the speed of
the boat.
So, what is the speed of the boat?
Let us suppose, x km per hour.
So, keep these two things in mind.
In the formulas that I am going to show you, we will use
this, that we will let the speed of the stream be y, and
the speed of the boat in still water, what will we let? x
km per hour.
Now, when our water body, that stream is running, and in
whose contact is it?
In the contact of the boat.
In the contact of the boat and the water body, only then,
that water body, that stream, what is it doing to the speed
of our boat?
It is influencing the speed of the boat.
Unlike the case of train.
In the case of train, it was not like that.
When our two trains were moving, they were not influencing
each other's speed.
They were moving at their own speed.
And the other train, the man or whatever it was, it was
moving at its own speed. Both the bodies were not
influencing each other's speed.
But, in this case, in the case of boat and stream, this
stream, what will it do to the speed of our boat?
It will influence it.
So, obviously it will influence the speed of the other one
as well.
Because both are in contact.
Both are touching each other.
So, the speed of one will influence the speed of the other.
So, if we look at the cases of downstream.
So, if we have a case of downstream.
So, what will be the formula of speed of downstream?
I will denote speed of downstream with SD.
Now, if the water is flowing in the same direction and the
boat is also in the same direction.
So, it will be easy for the boat to flow.
Because there is no friction of water.
Whatever term of water you use in this, it is not coming
against the speed of the other.
It is flowing in the same direction.
So, what will be the speed of downstream in this?
The speed of the boat will be added up.
Means, the speed of the boat in still water and the speed
of the stream will be added up.
So, we will get the speed of downstream.
So, this is x plus y kilometer per hour.
Same case, if we look at upstream.
So, I will denote upstream with SU.
U means upstream.
If we are taking out speed, then I will denote it with SU.
What will happen to SU?
Now, if our boat is going against the flow.
What can we say indirectly?
That it is going against the stream, against the water flow.
Because it is going in the opposite direction.
So, what will happen then?
Then, the first thing that will happen is that the speed of
our boat will obviously have to be more than the speed of
the stream.
Only then it will be able to compete against it.
Otherwise, how will it be able to compete?
If its speed is less, then it will flow with it.
Because its speed is comparatively low.
It is less than that.
So, its speed, the speed of the boat in still water.
That should be greater than the speed of the stream.
Then what will happen to us? Only then our boat will be
able to go upstream.
Only then the boat will be able to flow in the opposite
direction.
Otherwise, it will not be able to do.
So, one condition will come in this.
That our x should be greater than the speed of the stream.
So, x should be greater than y.
So, when this will happen, then the difference will come.
x minus y.
That would be the speed of upstream.
So, x minus y.
Kilometer per hour.
So, you have understood all these terms.
What is x? x is the speed of the boat in still water.
The original speed of the boat in still water.
And what is y? y is the speed of the stream. Or the speed
of the water body that is given to us.
And what is S?
S is the speed of the downstream.
And this is the speed of the upstream.
What speed will we use to go upstream?
The relative speed that we use in that.
In this case, we will use the speed of the upstream.
Or we will use the speed of the downstream.
I hope this will be clear to you.
Now, let us see the questions.
What type of questions are these?
So, let us see the questions.
The question is.
Read this question.
In one hour, a boat goes 11 km per hour along the stream.
Mark this along the stream.
Along the stream means upstream or downstream?
Along means along the same stream.
So, whose case is this?
Along the stream means downstream.
And 5 km against the stream.
Whose case is this?
Upstream.
Hope you understand.
Language is not necessary.
You can write the word upstream or downstream.
Then the speed of the boat in still water is 8 km per hour.
What is given to us?
We are given in one hour.
This time is given.
In one hour, our boat is going downstream at this speed.
So, what is the speed of the downstream given to us?
What is given?
SD is given to be 11 km per hour.
And upstream, against the stream, what is the speed given
to us?
That is, SU is given to be 5 km per hour.
Both these things are given to us.
Time to cover both in one hour.
The boat is going upstream and downstream.
Means, it is going against the flow and along the flow.
So, how much time is it taking to cover both in one hour?
How much time is it taking to cover both?
One hour.
So, what we have to find out?
The speed of the boat in still water.
That is, we have to find out the value of x.
What is the value of x? x is the speed of the boat.
Let the speed of the boat in still water be x km per hour.
So, what was the speed of the stream? y km per hour.
This is the speed of the stream.
y km per hour and x km per hour of the boat.
We have to find out x.
So, what was SD?
What was the speed of the downstream? x plus y.
We can write it indirectly.
It means x plus y only.
And what is the meaning of the downstream?
Upstream means x minus y.
So, we have the value of x plus y.
And the value of x minus y is 5 km.
So, what is the equation?
The equation is x plus y is equal to 11 km per hour.
And x minus y is equal to 5 km per hour.
We have two equations.
We have two unknown variables.
x and y.
Two unknown variables and two equations.
So, we have minimum number of equations to solve two
unknown variables.
So, we have two unknown variables and two equations.
So, we can solve them and get the value of x and y.
How to do it?
If we add up both the equations.
Adding these two equations.
So, it will be x plus x.
Add it with the term.
How much will be x plus x? 2x.
And y minus y.
It will cancel out and become 0.
It is equal to 11 plus 5.
That is 16.
So, what is the value of x? 16 by 2. That is 8 km per hour.
This is what we required.
Speed of the boat in still water.
So, what we got? 8 km per hour.
We had to get it in km per hour.
So, we can also get y.
We were not asked.
But, if we are asked about y.
How will we get it?
In any of these equations.
If we put the value of x.
We will get y automatically.
If we put 8 in this first equation.
What will be the value of y? 11 minus 8. That is 3 km per
hour.
So, what will be the value of y? 3 km per hour.
You can see.
The speed of the boat is more than the speed of the stream.
That is why the boat was able to go upstream.
Because the speed of the boat was more than the speed of
the stream.
I had told you about that case.
Now, see.
As I have asked you this question.
I have asked you this question.
So, we can use this to make a formula.
We can build up.
That is.
What will be the formula?
If you see.
The speed of the downstream is x plus y.
We know this.
The speed of the upstream is x minus y.
If we solve both the equations.
If we add up both the equations.
What will we get?
If we add.
We will get.
So, we can directly get the value of x.
If we take the speed of the boat.
Downstream and upstream.
x will be sd plus su divided by 2.
This is speed of the boat in still water.
Speed of the boat in still water.
Similarly, if we subtract this.
We have just added.
If we subtract this.
What will happen to us? If we subtract this, the sign will
change.
I will write in the new slide.
sd is equal to x plus y and su is equal to x minus y.
If we do both of them, subtract both of them.
To subtract because we have to do x.
We have to cancel both of them.
If we subtract, the sign will change.
Here it will be minus.
Here it will be plus.
If x is in plus, it will be minus.
If y is in minus, it will be plus.
Now solve this.
This would be sd minus su is equal to x minus x.
Cancel out.
It will be zero.
would be 2y.
So what is the value of y? y is sd minus su divided by 2.
And what was y? y is speed of the stream.
Speed of the stream will be sd downstream minus speed of
the upstream divided by 2.
So speed of the boat in still water and speed of the stream
can be taken out directly with the help of speed of the
downstream and speed of the upstream.
This formula is not necessary.
You can remember it.
With the help of this, like I did this question, I did not
use the formula in this question.
I directly put up what we knew and solved it.
But if you remember it, then no problem.
You can do it like this and directly using the formula.
So this was an easy question.
Let us see the next question.
Let us see what is given in this question.
A boat covers a certain distance downstream in one hour.
While it comes back in one and a half hour.
Indirectly what is given? Time of upstream is given.
That is, time of upstream is given as one and a half hours.
If the speed of the stream is 3 km per hour, then y is
given to
be 3 km per hour.
What is the speed of the boat in still water? Speed of the
boat is denoted by x.
So what do we have to find out? We have to find out the
value of x.
So let us see the question.
A boat covers a certain distance downstream in one hour.
If it is
going downstream in one hour. Suppose it starts from here.
It is going downstream in one hour.
And if it is coming back upstream, then it will be the same
distance.
Because we have covered a certain distance.
We have not covered a different distance.
Come back.
If it is going, then it will cover the same distance and
come back.
So it is coming, covering the same distance.
Let us suppose we give the name of that distance.
Capital D distance.
So in return back, our upstream will be upstream.
And how long is it coming? In one and a half
hours. If we convert one and a half hours, then it will be
3 by 2 hours.
Do you know how to convert mixed fraction into improper
fraction? How? 2 into 1 plus the upper one remainder 1.
So 2 into 1 is 2 plus 1 is 3.
So what do we have? 3 by 2 hours.
Now see what is the constant in this? Which is same in both.
That is distance D.
So the distance which we have covered upstream and
downstream, what is the distance in both? That is same
D distance. So if the distance is same, then we can equate
both by applying distance formula.
Because we have given Y, we need X.
So if we get upstream or downstream, then we can find out
the value of X with the help of it or not? We can obviously.
So once you see that what will be the speed of downstream?
What is the speed of downstream? X plus Y.
So how much will be X plus Y? X is not given.
Let us keep X as X.
And Y will be 3 km per hour.
So what is the speed of downstream? X plus 3 km per hour.
Similarly, what will be the speed of upstream? X minus Y.
That is X minus 3 km per hour.
Take the case of upstream and downstream individually.
And apply the distance formula in it.
Because the distance is same in both upstream and
downstream.
So if we equate that distance because both have same
distance, then our unknown value X will come or not? So I
will make an equation and tell you.
What will happen if we see the case of downstream?
So for the case of downstream, what will be the distance?
What will be the distance?
Speed into time will be the distance.
So distance that is D is equal to speed into time.
This is our general formula.
If we are doing for downstream, then for downstream we will
keep
D as downstream and time that is 1 hour.
So what will be the value of T? We will write
T as 1 so that we can get clarity that we are using
downstream.
So we will keep that as 1 hour.
So D is same.
We have added distance D.
So D is equal to SD that is X plus 3 into 1.
Similarly, if we do the case of upstream, then the distance
D will be equal to speed into time.
Now if we are taking upstream, then we will take upstream
speed as SU and time will be 3 by 2 hours.
So we will denote it as T2.
So this distance D is same.
D is equal to what? X minus 3 into 3 by 2.
Now if you equate both of them, then both are equal to D.
So if we have two things equal to same thing, then what
will happen to those two things? They will become equal.
So equate them.
What will happen? X plus 3 will be equal to X minus 3 whole
into 3 by 2.
Now multiply 2 here.
What will happen? 2X plus 6 is equal to 3X minus 9.
Solve it.
Take 2X here.
Take minus 9 here and it will be plus 9.
So it will be 3X minus 2 that is X and what will happen? 6
plus 9 that is 15 and what is our
X? It is speed.
So it would be 15 km per hour.
This would be our answer.
That is the speed of the boat in still water.
What we have? 15 km per hour.
It was easy.
Whatever values were given to us, we put them.
We were given Y.
So we put Y in upstream and downstream formula in speed.
Then the constant thing in both of them was distance.
We equated it
in both of them and put it in distance is equal to speed
into time formula and with the help of that, we found out
the value of X unknown variable.
So now moving on to next question.
Read this question once and see how much it is getting
solved.
Question So, the question says
A man has to go from a port to an island and return.
First he is going from the port to the island and then he
is returning.
So, let us suppose if our point P is a port.
So, where is he going from the port? He is going to an
island.
Suppose this is our island.
And then he is returning back also.
So, what is this whole thing? It is a journey.
Which is given in this question.
He can row a boat with a speed of 7 km per hour in still
water.
Speed of boat in still water is given.
That is x is given.
So, x is equal to 7 km per hour is given to us.
The speed of the stream is also given.
That is 2 km per hour.
What is the speed of the stream? y is equal to 2 km per
hour.
So, this is given to us.
If he takes 56 minutes to complete the round trip.
What does it mean?
He took 56 minutes to complete the round trip.
Round trip means the whole trip that we have been told.
Means first from port to island and then back from island
to port.
The distance that he has covered, he has completed it in 56
minutes.
That is total time taken is equal to 56 minutes.
Then, find the distance between the port and the island.
What we have to find?
Distance between the port and the island.
How much will it be?
We have to find out this distance.
Port to island or island to port will be same distance.
So, what we have to do? We have to find out.
So, how will we do?
Let's see the question.
First of all, what is given to us? x is equal to 7 km per
hour and y is equal to 2 km per hour. Now, once he is going
and once he is coming.
So, once his upstream, once his against the flow of the
stream and once his along the flow.
So, in this, both the streams are there.
Downstream and upstream are also there.
So, what we do first?
We find out the speed.
What will be the speed of downstream? x plus y, everyone
knows the formula. That is 7 plus 2 km per hour.
So, how much we have? 9 km per hour.
This is our downstream speed, SD.
Similarly, SU, upstream speed will be x minus y.
So, x is greater than y.
So, it can go upstream also.
So, 7 minus 2 will be there.
That is 5 km per hour.
This is our upstream speed.
Now, if total time taken is given.
So, how much time it will take to go and how much time it
will take to come.
We will add those two.
So, that will give us total time.
Will it give or not?
Obviously, it will give.
So, the time to go and the time to come.
The time to go and the time to come back.
If we add those two, then we will get total time.
That is time taken from port to island.
Time taken from port to island.
Port for i plus time taken to return back.
Return back.
Return back from where?
From island to port.
Island to port.
The sum of these two will be equal to total time taken.
That is equal to 56 minutes.
Now, we have to find out the time taken from P to I.
That is time taken to go and time taken to come.
The time taken to go will be upstream and time taken to
come will be downstream.
Obviously, the opposite will be downstream.
So, what we have to find out?
We will use the formula of time.
What is the formula of time?
Time is equal to distance upon speed.
This is our time formula.
Suppose, we are taking d which is unknown.
We take d.
What are you considering?
What are you considering P to I? You can consider
downstream.
You can consider upstream.
So, d will come below P to I.
Plus, the distance to return back is also same.
So, we will take d for that also.
But, for that, the speed will be upstream.
So, this is the time taken from port to island.
This is the time taken from island to port.
This is equal to total time.
That is 56 minutes.
Now, look at this.
This is in km per hour.
So, this unit should also be in hours.
Only then, all the units will be same.
Only then, we can equate and solve this.
So, you convert 56 minutes into hours.
Now, how can we do this in 60 minutes?
Look at this side.
In 60 minutes, we have equal to 1 hour.
So, 1 minute is equal to 1 by 60 hours.
Similarly, when we get 1 minute, then 56 minutes will be
equal to 56 into 1 by 60 hours.
That is, cancel out 4.
4 times 1 is equal to 14.
So, this will be 15.
So, this is 14 by 15 hours.
So, we can write 56 minutes as 14 by 15 hours.
So, write here 14 by 16 hours.
So, all this is in hours or km per hour.
So, the distance will be in km.
Now, put the value and solve it.
Erase this figure.
Now, solve it.
If you put value of SD, it will be 9.
So, it will be D by 9 plus D by SU value 5 is equal to 14
by 15.
Solve it. Take LCM.
9 into 5 is equal to 45.
5D plus 9D is equal to 14D.
It is equal to 14 by 15.
14 by 14 is equal to 15.
15 by 15 is equal to 45.
So, D is equal to 3 km.
This is what we required.
This is the distance between port and island.
So, we took D.
So, that is 3 km.
It was easy.
What you have to do in this?
You can do it in another method.
But, if you apply the same concept, if you apply the
correct concept, then your answer will be correct.
So, whichever method you are comfortable with, whatever
concept you feel is correct, you can do it.
No problem in that.
Now, moving on to next question.
See this question.
Read it.
So, the question says,
A racer can row a boat 30 km upstream and 44 km downstream
in 10 hours.
See the difference in this question.
So, what was this?
In the previous questions, we used to get a speed from
upstream and downstream or we used to get the speed of the
still water.
But, in this, there is no speed.
In this, the distance we have covered, upstream and
downstream,
that is 30 km upstream and 44 km downstream.
And, how much time did we cover? In 10 hours.
That means, that racer.
He can now...
He can row 40 km upstream, which is one more case for which
it has been told.
It has been told that he can row 40 km upstream and 55 km
downstream in 13 hours.
So, find the speed of the boat in still water, that is, we
have to find out the value of x and the speed of the
stream, that is, we have to find out the value of y.
So, how will we do this question?
We have not been given x or y in this, we have just been
given distance and time.
As soon as you are hearing that distance and time have been
given, what should come to mind?
Speed should come, speed can only come out of them and when
that speed comes, then we will solve further.
So, let's solve this question.
A racer can row 30 km upstream and 44 km downstream in 10
hours.
If we see that we have been given time of 10 hours, then
the time it will take to go upstream plus the time it will
take to go downstream, if we add up both, then 10 should
come in the first case.
Similarly, in the second case also, the time it will take
to go upstream and the time it will take to go downstream,
if we add them up, then how much time should we get?
We should get 13 hours.
So, what we are taking in this, we are going by equating
time.
Okay, we have to equate time.
So, let's take the speed of upstream.
What is the speed of upstream?
It is Su, speed of upstream.
Similarly, what is Sd denoting?
Speed of downstream.
Speed is same.
If you do, then 30 km upstream is going, that is the
distance given.
This is our distance.
So, distance and speed.
If we do distance upon speed, then time will come.
So, the time it took to go upstream, time for upstream,
means time going for upstream,
I am writing this in short, plus time for downstream. If we
add up both, then in the first case, we should get the
equal of total time, that is 10 hours.
Similarly, if we do the second case, then we should get 13
hours.
So, in the first case, what will happen? Distance upon
speed.
So, distance is 30, speed is Su, plus, for this, distance
is 44, and speed is Sd.
Whose is this equal?
It is equal to 10 hours.
This is our first equation.
Now, second equation.
We will do the same with the second case.
Time for upstream plus time for downstream.
How much should we get for downstream?
It should be equal to 13, because 13 hours are given here.
So, what will happen? 40 upon upstream, so S of u, plus 55
downstream.
So, speed will be downstream.
Whose is this equal to? It is equal to 13 hours.
Now, we have two unknown values.
Su and Sd are unknown to us.
So, how many equations do we have?
We have two equations.
So, we have two equations and two unknowns.
At least, we should have as many equations as unknown
variables.
So, we can easily find them out.
So, what should we do?
For the shortcut,
Su, 1 upon Su, what is this? 1 upon Su, 1 upon Sd.
So, consider 1 upon Su as u, and consider 1 upon Sd as v.
For the shortcut, we will reciprocate the answers later.
We will get them.
So, what will happen? 30u plus 44v is equal to 10.
What is the second equation? 40vu plus 55v is equal to
We have to make the same coefficient of any of the terms.
So, we will make the coefficient of u equal to 30 and 40.
So, multiply the first equation by 40 and multiply the
second equation by 30.
When you do this, what will be the result of the new
equation?
I will write the new equation here.
I am writing it on this side.
We will go to the next page.
40 into 30 is equal to 1200v plus 40 into 44 is equal to 16.
1760v is equal to 400.
This is the first equation.
Next equation is 1200v plus 55 into 3 is equal to 30.
15, 1, 16 1650u Sorry, the first one is u and the second
one is v.
This is equal to 13 into 30 is equal to Let me rub this.
You can note it down.
30 into 13 is equal to 390.
Now, solve both the equations.
Subtract them.
Minus and minus cancel.
What will be the result of this? 0, 1 6 into 7 is equal to
110v is equal to 10.
What will be the value of v? v will be 0 into 0 is equal to
1 by 11. v is equal to 1 by 11.
What was v? 1 by sd. What will be the value of sd? Sd is
equal to 11 km per hour.
11 km per hour.
This is our downstream speed.
When v is equal to 1, we will subtract u.
If we substitute v here, we will get u.
If we substitute sd here, we will get v.
v is equal to 1 by 11.
1 by 11 is equal to 4.
30u plus 4 is equal to 10.
30u is equal to 6.
6 by 30 is equal to 1 by 5.
But we have to take reciprocal of u for s to find su.
We will get su.
1 by u is equal to 5 km per hour.
We have got sd and su.
We have got upstream speed and downstream speed.
We can subtract x and y.
How will we do it?
Let's go to the next page.
How will we do it?
We have got sd and su.
We have got sd 11 km per hour and su is equal to 5 km per
hour.
What is the value of sd? x plus y
You can either do this x minus y
I have told you the short formula earlier.
In reverse, what is the value of x? sd plus su divided by 2
is equal to 11 plus 5 divided by 2 is equal to 16 by 2 is
equal to 8 km per hour.
Similarly, what is the value of y? sd minus su by 2 is
equal to 11 minus 5 is equal to 6 by 2 is equal to 3 km per
hour. This is the answer.
The value of y is equal to the speed of the stream is equal
to 3 km per hour and speed of the boat in still water is
equal to 8 km per hour.
I hope you have understood the concept of boat and stream.
I hope you have understood the concept of speed for
downstream and upstream.
I hope you have understood how to solve these questions
using these formulas.
I hope you have understood how to solve these questions
using these formulas.
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