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1. A boat goes 13km upstream in 39 minutes. The speed of stream is 3km/hr. The speed of boat in still water is-
- A. 27km/hr
- B. 27km/hr
- C. 27km/hr
- D. 27km/hr
Answer: Option D
Explanation:
Let speed of the boat is u kmph
Speed of the stream is v = 3 kmph
Time taken t = 39 min = 39/60 hour
Distance s = 13 km
We have
u - v = s/t
u - v = 13/(39/60) = (13×60)/39 = 20
= > u - 3 = 20
= > u = 20 + 3 = 23
Ans 23 kmph.
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