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Answer» Speed of man in still water= 6km / h speed of stream( Ss) = 1.2 km /h speed downstream(Sd) = speed of man in still water + speed of stream =6 + 1.2 = 7.2 km /h speed upstream(Su)= speed of man in still water - speed of stream =6 - 1.2 = 4.8 km /h let T = time taken time downstream + time upstream = 1 h Td + Tu = 1 h since ,we know Time = distance/speed , D / Sd + D/Su = 1 D /7.2 + D /4.8 = 1 4.8D + 7.2D = 1 × 7.2 × 4.8 12D = 34.56 D = 34.56 / 12 D= 2.88 km therefore , distance(D) = 2.88 km |
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