Multiple choice

A robber is noticed by a policeman from a distance of 200 m. After noticing the policeman, the robber starts running and the policeman chases him. If the rates of speeds of the policeman and the robber respectively are 11 km/h and 10 km/h, find the distance between them after 9 minutes.

  1. 210 m

  2. 10 m

  3. 50 m

  4. 197.5 m

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

Relative speed = 11 - 10 = 1 km/h = 1000/60 m/min = 50/3 m/min. In 9 minutes, the policeman covers (50/3) * 9 = 150m more than the robber. Initial distance was 200m, so remaining distance = 200 - 150 = 50m.

AI explanation

The relative speed of the policeman and the robber is 11 km/h minus 10 km/h, which equals 1 km/h, or 1000/60 meters per minute. In 9 minutes, the policeman closes the gap by 1000/60 multiplied by 9, which equals 150 meters. Subtracting this closed gap from the initial 200 m distance leaves them 50 m apart.

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