Question

A boat covers 1200 km distance whose downstream speed is y kmph and the speed of the boat upstream is 60% of the speed of the boat downstream. If the difference between the time taken by the boat upstream and downstream is 32 hours. Find the distance covered by the boat in 5 hours if they traveled with the speed of still water.

• A. 110 km
• B. 150 km
• C. 100 km
• D. 130 km

Answer 1

Answer:

C. 100 km

Explanation:  Distance covered = 1200km

Downstream speed of the boat = y kmph

Upstream speed of the boat  = $\frac{60}{100}\times{y} = 0.6y$

If the difference between the time taken by the boat to travel upstream and downstream is 32 hours

$\frac{1200}{0.6y}-\frac{1200}{y} = 32$

$\frac{2000}{y}-\frac{1200}{y} = 32$

$\frac{800}{y} = 32$

Downstream speed of the boat y = 25 kmph

Upstream speed of the boat y $= 25\times{(0.6)} kmph = 15 kmph$

Speed of the boat in still water $= \frac{(25 + 15)}{2} = 20 kmph$

Distance covered by the boat in still water in 5 hours $= 20\times{5} = 100km$