Boats and Streams

Quantitative Aptitude (CGL)

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Indian Economy - Understanding the basics of Indian economic system

The speed of a motor boat in still water is 20 km/h.It travels 150 km downstream and then returns to the starting point. If the

round trip takes a total of 16 hours, what is the speed (in km/h) of the flow of river?

This questions was previously asked in

SSC CGL 24th August 2021 Shift-3

- Let's denote the speed of the river flow as \( v \) km/h.

- Then, the effective speed downstream is \( 20 + v \) km/h and upstream is \( 20 - v \) km/h.

- The time taken to travel downstream 150 km is \( \frac{150}{20 + v} \) hours.

- The time taken to travel upstream 150 km is \( \frac{150}{20 - v} \) hours.

- The total time for the round trip is given: 16 hours.

- Setting up the equation: \(\frac{150}{20 + v} + \frac{150}{20 - v} = 16 \).

- Solving for \( v \), we find \( v = 5 \).

- Option 1: If \( v = 8 \), it doesn't satisfy the equation.

- Option 2: If \( v = 6 \), it doesn't satisfy the equation.

- Option 3: If \( v = 5 \), it satisfies the equation.

- Option 4: If \( v = 4 \), it doesn't satisfy the equation.