Question

Mr.Aman, rowing a boat, cover a distance of 48 km in 3 hours downstream. He covers (7/16) of the downstream distance on 3 hours when rowing upstream. Calculate speed of the stream.
1. 1.5 km/h
2. 4.5 km/h
3. 3.5 km/h
4. 2.0 km/h

Answer 1

Correct Answer - Option 2 : 4.5 km/h

Given

Distance covers in downstream = 48 km

Time taken in downstream = 3 hours

Distance covers in upstream = (7/16) of downstream distance

Time taken in upstream = 3 hours

Formula used

Speed of stream = (Downstream speed - Upstream speed)/2

Speed = Distance/Time

Calculation

Downstream speed = 48/3

= 16 km/h

Upstream speed = [(7/16) × 48]/3

= 21/3

= 7 km/h

Speed of stream = (16 - 7)/2

= 9/2

= 4.5 km/h