Multiple choice

8 girls and 12 boys can complete a work in 4 days. If one boy alone completes the work in 60 days, then in how many days a girl will be able to finish the same work alone?

  1. 150

  2. 140

  3. 160

  4. 144

  5. 156
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

1 boy takes 60 days, so 1 boy's 1-day work = 1/60. 12 boys' 1-day work = 12/60 = 1/5. 8 girls + 12 boys take 4 days, so (8G + 12B) 1-day work = 1/4. 8G + 1/5 = 1/4. 8G = 1/4 - 1/5 = 1/20. 1G = 1/160. A girl takes 160 days.

AI explanation

Since one boy completes the job in 60 days, his daily work is 1/60, making the daily work of 12 boys equal to 12/60 or 1/5. If one girl takes G days, the daily work of 8 girls is 8/G. The combined daily work of 8 girls and 12 boys is 1/4, so 8/G + 1/5 = 1/4. Solving 8/G = 1/20 gives G = 160.

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