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A sailor goes 12 km downstream in 48 minutes and returns in 1 hour 20 minutes. The speed of the sailor in still water is :
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- 12 km/hr
- 12.5 km/ hr
- 13 km/hr
- 15 km/hr
- 12 km/hr
Correct Option: A
Let the speed of sailor in still water be p kmph.
and Speed of current = q kmph
| ∴ p + q = | ||||
| 60 | ||||
| p + q = | × 60 = 15 kmph ........( 1 ) | |
| 48 |
| and, p - q = | ||||
| 60 | ||||
| p - q = | = 9 kmph ........( 2 ) | |
| 80 |
Adding equations ( 1 ) and ( 2 ) , 2p = 15 + 9 = 24
⇒ p = 12 kmph
Second method to solve this question :
| Here, p = | × 60 = 15 kmph | |
| 48 |
| q = | ||||
| 3 | ||||
q = 9 km/hr
| Speed of Boat = | (p + q) | |
| 2 |
| Speed of Boat = | (15 + 9) = 12 kmph | |
| 2 |
