Multiple choice

If 6 boys or 12 girls can complete a piece of work in 24 days, then how many days will 5 boys and 8 girls take to complete the work?

  1. 20 days

  2. 18 days

  3. 14 days

  4. 16 days
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

6 boys complete work in 24 days, so 1 boy takes 144 days. 12 girls complete work in 24 days, so 1 girl takes 288 days. Work rate of 1 boy = 1/144 per day, 1 girl = 1/288 per day. Combined rate of 5 boys + 8 girls = 5/144 + 8/288 = 10/288 + 8/288 = 18/288 = 1/16 per day. Therefore, they complete the work in 16 days. Option A (20 days) would require a slower combined rate. Option B (18 days) and C (14 days) don't match the calculated rate.

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