Multiple choice

A boat can cover 9.6 km upstream in 24 minutes. If the ratio of speed of the current to speed of boat in still water is 1: 4, then how much distance (in km) can the boat cover downstream in 36 minutes?

  1. 19

  2. 27

  3. 24

  4. 29.5

  5. None of these
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Upstream speed = 9.6/24 = 0.4 km/min. If current:boat = 1:4, then boat = 4c, upstream = 3c = 0.4, so c = 0.133 and boat = 0.533. Downstream = boat + current = 5c = 0.667 km/min. In 36 min: 0.667 × 36 = 24 km.

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