Correct Answer - Option 2 : 14 hours
Given:
Distance covered upstream = 24 km
Distance covered downstream = 20 km
Speed of boat in still water = 6 km/hr
Speed of stream = 4 km/hr
Concept used:
Upstream speed = Speed of boat in still water – Speed of stream
Downstream speed = Speed of boat in still water + Speed of stream
Calculation:
Upstream speed = (6 – 4) km/hr
⇒ 2 km/hr
Downstream speed = (6 + 4) km/hr
⇒ 10 km/hr
Time taken to cover 24 km upstream = 24/2 hours
⇒ 12 hours
Time taken to cover 20 km downstream = 20/10 hours
⇒ 2 hours
Total time taken to cover the whole journey = (12 + 2) hours
⇒ 14 hours
∴ The total time taken to cover whole journey is 14 hours
