Multiple choice

(\text{The upstream speed of the boat is 40 km/hr and the speed of the boat in still water is 55 km/hr. What is the downstream speed of the boat?})

  1. 75

  2. 80

  3. 70

  4. 65
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Let the boat speed in still water be b and the stream speed be c. Given: upstream speed (b - c) = 40 km/hr and boat speed b = 55 km/hr. Therefore, stream speed c = b - upstream speed = 55 - 40 = 15 km/hr. Downstream speed = b + c = 55 + 15 = 70 km/hr. This is a standard boats and streams problem where downstream speed equals the sum of boat and stream speeds.

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