Question
Manyata rowed a certain distance downstream in 2 hours
while it took her 30 minutes more to row the same distance upstream. How much time will she take to make the two-way journey in still water?Solution
Let B be the speed of the boat in the still water and S be the speed of the water. Now, The downstream speed = (B + S) The upstream speed = (B - S) According to the question, (B + S) × 2 = (B - S) × 2.5  0.5B = 4.5S  B/S = 4.5/0.5  B/S = 9/1 Let the common ratio be X. The speed of the boat in still water is 9x and the speed of the water x. Rowing distance = (B + S) × 2 = (9x + x) × 2 = 20x Time taken to complete the two-way journey in still water. (20x x 2)/9x = 4(4/9) h. = 4 hours (4/9) ×60) minutes = 4 hours 26 minutes 2/3 seconds = 4 hours 26 minutes (2/3× 60) seconds 4 hours 26 minutes 40 seconds  She will take 4 hours 26 minutes 40 seconds to make the two-way journey in still water.
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