Question

6.Ram can row a boat in still water at 10 kmph. He decides to go boating in a river. To row upstream he takes 2 hours and to row downstream he takes 1 ½ hours. Find the Speed of the river​

Answer 1

Answer:

Speed of river = 10/7 kmph

Step-by-step explanation:

Suppose the Speed of the river is ‘y’ kmph.

While rowing upstream he takes 2 hrs and while rowing downstream he takes 1 ½ hours.

As the Distance covered is constant the ratio of the net Speeds of the boat while going upstream and downstream will be the inverse of the ratio of the Time taken.

Ratio of Time taken (downstream: upstream) = 1.5/2 =3/4

So the ratio of Speed of boat (downstream: upstream) = 4/3

Speed downstream: 10 + y Speed upstream : 10 – y

(10+y)/((10-y) ) = 4/3

30+3y=40-4y. Thus, 7y=10 & Y=10/7

Speed of river = 10/7 kmph

Answer 2

Answer:

The speed of river =10/7 kmph

Step-by-step explanation:

Let the speed of river = y

speed of boat in still water = 10 kmph

speed of boat in upstream = speed of boat in still water- speed of river

                                             = (10-y) kmph

speed of boat in downstream = speed of boat in still water + speed of river

                                                  =(10+y) kmph

ratio of time(upstream/downstream=ratio of speed(upstream/downstrem

                              2/(3/2)=10+y/10-y

2(10-y)=3/2(10+y)

4(10-y)=3(10+y)

40-4y=30+3y

40-30=3y+4y

10=7y

y=10/7

so speed of river = 10/7