15 men take 21 days of 8 hrs. each to do a piece of work. How many days of 6…
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15 men take 21 days of 8 hrs. each to do a piece of work. How many days of 6 hrs. each would it take for 21 women if 3 women do as much work as 2 men?
- A.
30
- B.
20
- C.
19
- D.
29
Attempted by 8 students.
Show answer & explanation
Correct answer: A
Solution:
Convert the work into man-hours. Total work = number of men × days × hours per day = 15 × 21 × 8 = 2520 man-hours.
Convert women to equivalent men: 3 women = 2 men ⇒ 1 woman = 2/3 man. So 21 women = (2/3) × 21 = 14 men.
Let n be the number of days required when 21 women work 6 hours per day. Their daily output in man-hours = 14 × 6 = 84 man-hours per day, so total work done = 84 × n.
Equate total work: 84 × n = 2520 ⇒ n = 2520 ÷ 84 = 30.
Answer: 30 days.