Question

A boat has a speed of 12 km/h in still water and the speed of the stream is 3 km/h. It first covers 45 km in downstream and then travels upstream a distance which is x% less than the downstream distance. If the whole journey takes 5 hours, then find the value of ‘x’.

A 20 Correct Answer Incorrect Answer
B 60 Correct Answer Incorrect Answer
C 85 Correct Answer Incorrect Answer
D 30 Correct Answer Incorrect Answer
E None of these Correct Answer Incorrect Answer

Solution

ATQ, Distance covered by boat in upstream = [{1 − (x/100)} × 45] km Upstream speed of the boat = 12 − 3 = 9 km/h Downstream speed of the boat = 12 + 3 = 15 km/h According to the question; [{{1 − (x/100)} × 45} / 9] + (45 / 15) = 5 Or, {1 − (x/100)} × (45/9) = 5 − 3 Or, {1 − (x/100)} × 5 = 2 Or, 1 − (x/100) = 2/5 Or, (x/100) = 1 − 2/5 = 3/5 Or, x = 60

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