Question

A fish swins 12 miles upstream in 4 hours. The return trip only takes 3 hours. Find the rate of the current

Answer 1

1/2 mph

Explanation:

Given :

Distance traveled, D = 12 miles

Upstream Swim time = 4 hours

Return swim time = 3 hours

Upstream rate = 12/4 = 3 mph

Return rate = 12/3 = 4 mph

Let

swim rate = s

Current rate = c

s - c = upstream rate

s + c = return rate

s - c = 3 - - - (1)

s + c = 4 - - -(2)

From (1)

s = 3 + c

Put into (2)

3 + c + c = 4

3 + 2c = 4

2c = 4 - 3

2c = 1

c = 1/2 mph

Hence, rate of current = 0.5mph