Discuss Forum
1. A boat covers 143 km upstream in 13 hours and the same distance downstream in 11 hours. What is the speed (in km / hr ) of the boat in still (without stream) water?
- A. 10 km/hr
- B. 10 km/hr
- C. 10 km/hr
- D. 10 km/hr
Answer: Option B
Explanation:
Let the speed of the boat and speed of the stream be x km/hr and y km/hr respectively
According to the question,
143 / (x - y) = 13 - (- - - (i))
143 / (x + y) =11-***=(ii)
On comparing both eq
11(x + y) = 13(x - y)
11x + 11y = 13x - 13y
24y = 2x
x / y = 12/1
Ans: Speed of the boat in still water is 12 km/hr
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