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JAMB Mathematics 1987 Question 11

Question 11

Ratio, Percentages and Rates

Four boys and ten girls can cut a field in 5 hours. If the boys work at 5/4 hrs rate of which the girls work, how many boys will be needed to cut the field in 3 hours?

  1. A.180
  2. B.60
  3. C.25
  4. D.20
Show the answer and explanation

Answer: D (20)

Explanation

A boy does 5/4 of a girl's work, so 10 girls equal 8 boys and the team is 12 boys working 5 hours (60 boy-hours). To finish in 3 hours needs 60 ÷ 3 = 20 boys.