A guy rowing to a location 48 kilometres away and returning after 14 hours. He discovers that rowing 4 kilometres with the stream takes the same amount of time as rowing 3 kilometres against it. The stream is moving at the following rate:
A. 1 km/hr
B. 1.5 km/hr
C. 2 km/hr
D. 2.5 km/hr
Answer:A
A guy rowing to a location 48 kilometres away and returning after 14 hours. He discovers that rowing 4 kilometres with the stream takes the same amount of time as rowing 3 kilometres against it. The stream is moving at the following rate:
A. 1 km/hr B. 1.5 km/hr C. 2 km/hr D. 2.5 km/hr
Explanation: Assume he travels 4 kilometres downstream in x hours. Then,Downstream speed = 4/x km/hr.Upstream speed = 3/x km/hr,x = 1/2 = 48/(4/x) + 48/(3/x) = 14.So, downstream speed is 8 km/hr, while upstream speed is 6 km/hr.1/2 (8 - 6) km/hr = 1 km/hr is the rate of the stream.