The ratio of the speed of boat ‘A’ in still water, the speed of boat ‘B’ in still water and the speed of the current is 7:5:2, respectively. If the time taken by boat ‘A’ to travel (7D – 40) km downstream is equal to the time taken by boat ‘B’ to travel (D + 70) km upstream, then find the value of ‘D’.
Let, the speeds of boat ‘A’ and boat ‘B’, in still water and the speed of the current be 7x km/hr, 5x km/hr and 2x km/hr, respectively. According to the question, (7D – 40)/(7x + 2x) = (D + 70)/(5x – 2x) Or, 21D – 120 = 9D + 630 Or, 12D = 750 Or, D = 62.5
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