3) A boat travels 30km unstream in the same amount anstream of time it takes to travel 6o km downstream in the same river. If the speed of the river is 4 km/h, find the speed of the boat in still water.
Answers
Answer:
e will assume the speed of the boat is x. Since the rate of the stream is given in the question i.e. 5 kmph, we will add this speed of stream to the speed of the boat putting signs according to upstream and downstream.
Step-by-step explanation:
So, let the speed of the boat that we have to calculate be x.
Now, as the boat travels upstream with speed x and the rate of stream is 5 kmph, we will have-
Speed of boat in upstream: (x−5)
As the boat travels downstream with speed x and the rate of stream is 5 kmph, we will have-
Speed of boat in downstream: (x+5)
Now, as we all know the formula of speed is-
speed=dt (Where d stands for distance and t stands for time)
So, from above formula, the formula for time will be-
t=ds (Where t stands for time, d for distance and s for speed)
Now, as the time period is given same, we will have:
ds (for upstream) = ds (for downstream)
⇒30x−5=50x+5⇒3x+15=5x−25⇒15+25=5x−3x⇒40=2x⇒x=20
Thus, the speed of the boat is 20 kmph.
Step-by-step explanation:
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