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In a river, the ratio of the speed of stream and speed of a boat in still water is 2 : 5 Again, ratio of the speed of stream and speed of an another boat in still water is 3 : 4. What is the ratio of the speeds of the first boat to the second boat in still water ?
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- 10 : 7
- 15 : 8
- 4 : 3
- 5 : 4
Correct Option: B
For the first boat,
Speed of stream : Speed of boat = 2: 5
Let speed of stream be 2x km/h and speed of boat = 5x km/h
Similarly, for the second boat
Speed of stream be 3y km/h and speed of boat = 4y
In both of the conditions, river is same.
∴ 2x = 3y
⇒ x = 3y/2
Thus, required ratio in speeds of boats in still water
= Thus, required ratio in speeds of boats in still water
= 5x : 4y = (5 x 3)y/2 : 4y = 15 : 8
