Question
Time taken by boatman to travel a distance of (d + 60)
km downstream and (d + 120) upstream is 10 hours and 20 hours respectively, and the downstream speed of boatman is 25% more than speed of boatman in still water. Find the value of 'd'.Solution
ATQ; Let, the speed of boat in still water and stream speed be ‘B’ km/hour and ‘s’ km/hour respectively. According to question, (B + s) = 1.25 × B 0.25B = s B = 4s … (i) Also, (d+ 60) = 10(B + s) Using equation (i), we get, (d + 60) = 10(4s + s) = 50s … (ii) Also, (d + 120) = 20(B – s) Using equation (i), we get, (d + 120) = 20(4s - s) = 60s … (ii) Using equation (ii) and (iii), we get, (d + 60)/5 = (d + 120)/6 6d + 360 = 5d + 600 d = 600 – 360 = 240
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