A man can row a distance of 8 km downstream in a certain time and can row 6 km upstream in the same time. If he rows 24 km upstream and the same distance downstream in $1 \frac{3}{4}$ hours, then the speed (in km/h) of the current is:
Answer & explanation
Correct answer: option 2
We know that,
Speed = D/t
D= Distance
t = time
We have,
Total distance = 24km
Time taken = 7/4 hours
Let the speed of man and current be v and s respectively.
According to the question,
8/(v+s) = 6/(v−s)
= 8v - 8s = 6v + 6s
= 2v = 14s
= v : s = 7 : 1
Let speed of man = 7x
Speed of current = x
So,
24/8x + 24/6x = 7/4
= 3/x + 4/x = 7/4
= 7/x = 7/4
= x = 4
= speed of the current = 4 km/h