Question

Ajit can row a quarter of a km against the stream flow in 11¼
minutes and return in6¼
minutes. The speed of Ajit in still water is:​

Answer 1

Answer:

Speed of Ajit in still water is 14/27 m/s

Step-by-step explanation:

Let the speed of stream be u and the speed of Ajit in still water be v

Speed upstream = v - u

Speed downstream = v + u

A quarter of km = 1/4 km = 1000/4 m = 250 m

Time taken upstream = 11+1/4 = 45/4 minutes = 45/4 × 60 seconds = 675 seconds

Time taken downstream = 6 + 1/4 = 25/4 minutes = 25/4 × 60 seconds = 375 seconds

Using

Distance = Speed × Time

250 = (v - u) × 675

or, v - u = 250/675

or, v - u = 10/27  ....... (1)

Again

250 = (v + u) × 375

or, v + u = 250/375

or, v + u = 2/3   ............(2)

Adding equations (1) and (2)

2v = (10/27) + (2/3)

    = (10 + 18)/27

    = 28/27

or, v = 14/27 m/s

Therefore, the speed of Ajit in still water is 14/27 m/s