Multiple choice

A boat running downstream covers a distance of 60km in 4 hours. If the speed of the water current is half that of the boat, then what is the speed of the boat?

  1. 20 km/hr

  2. 10 km/hr

  3. 5 km/hr

  4. 40 km/hr
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Downstream speed = 60km / 4h = 15 km/hr. Let boat speed be B and current speed be C. B + C = 15. Given C = B/2, so B + B/2 = 15 => 1.5B = 15 => B = 10 km/hr.

AI explanation

The boat covers 60 km in 4 hours downstream, so the downstream speed is 60 km divided by 4 hours, which equals 15 km/hr. Let the speed of the boat be b and the speed of the current be c; given c is half of b, the downstream speed is b plus c, which equals b plus 0.5b, or 1.5b. Setting 1.5b equal to 15 km/hr gives b equal to 10 km/hr.

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