Question

The time taken by the boat can travel 240 km distance along the stream is equal to the time taken by the boat can travel 144 km distance against the stream. The speed of the boat is 20 km/hr. Find the speed of the stream.

• A. 3 km/hr
• B. 2 km/hr
• C. 5 km/hr
• D. 4 km/hr

Answer 1

Answer:

C. 5 km/hr

Explanation: 

Speed of the boat = 20 km/hr

Downstream distance = 240 km

Upstream distance = 144 km

Speed of the stream = y km/hr

$\frac{240}{(20 + y)} = T$ —– (1)

$\frac{144}{(20-y)} = T$ —— (2)

Equate both the equation

$\frac{240}{(20 + y)} =\frac{144}{(20-y)}$

$\frac{5}{(20 + y)} = \frac{3}{(20-y)}$

60 – 3y = 100 + 5y

5y = 40

y = 5 km/hr