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JAMB Mathematics 1991 Question 14

Question 14

Linear and Simultaneous Equations

A car travels from Calabar to Enugu, a distance of p km with an average speed of u km per hour and continues to Benin, a distance of q km, with an average speed of w km per hour. Find its average speed from Calabar to Benin.

  1. A.(p + q)/(up + wq)
  2. B.u + w
  3. C.uw(p + q)/(wp + uq)
  4. D.(wp + uq)/(up + wq)
Show the answer and explanation

Answer: C (uw(p + q)/(wp + uq))

Explanation

Total time = p/u + q/w = (pw + qu)/(uw). Average speed = total distance ÷ total time = uw(p + q)/(wp + uq).