a yacht travels 88 kilometres from point p and return downstream to the same point. what is the time taken by yacht to complete the journey if it's speed in still water is 12 km/hr and the speed of stream is 10 km/hr ?
A) 56 hours
B) 48 hours
C) 52 hours
D) 44 hours
Answers
Answer:
Time taken by the yacht for the complete journey is 48 hours.
Explanation and calculation:
Given information:
The distance the yacht travel while going upstream = 88 Km
The distance the yacht travel while going downstream = 88 Km
Speed of the river = 10 km/hr downstream
Speed of the yacht in still water = 12 km/hr
Now, since the river is flowing, it will decrease the speed of the yacht while travelling upstream, and, while its return trip, it will increase the speed of the yacht.
During the upstream trip:
Speed of the yacht = (12 - 10) km/hr = 2 km/hr [∵ the water and the yacht are moving in opposite directions]
Distance travelled by yacht = 88 Km
∴ Time taken by the yacht to travel upstream
= (distance ÷ speed)
= (88 ÷ 2) hours
= 44 hours
During the downstream trip:
Speed of the yacht = (12 + 10) km/hr = 22 km/hr [∵ the water and yacht are moving in the same direction]
Distance travelled by yacht = 88 Km
∴ Time taken by the yacht to travel upstream
= (distance ÷ speed)
= (88 ÷ 22) hours
= 4 hours
∴ Time taken by the yacht to complete the whole journey = (44 + 4) hours = 48 hours
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