Two cars X and Y start at the same point and travel towards a point P which is 150km away. If the average speed of Y is 60km per hour and x arrives at P 25 minutes earlier than Y. What is the average speed of X?
 

  • A 51\(\frac{3}{7}\)km per hour
  • B 72km per hour
  • C 37\(\frac{1}{2}\) km per hour
  • D 66km per hour
  • E 75km per hour
jamb 1981mathematics

The correct answer is B. 72km per hour

Let's solve this problem step by step:

1. Since car Y travels at an average speed of 60km per hour, it takes \(\frac{150}{60}\) = 2.5 hours to reach point P.
2. Since car X arrives at point P 25 minutes earlier than car Y, it takes 2.5 - \(\frac{25}{60}\) = 2.0833 hours to reach point P.
3. Since the distance between the starting point and point P is 150km, the average speed of car X is \(\frac{150}{2.0833}\) ≈ 72km per hour.

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