Multiple choice

A can do one - third of a work in 15 days, B can do 75% of the same work in 18 days and C can do the same work in 36 days. B and C work together for 8 days. In how many days will A alone complete the remaining work? A एक काम का एक तिहाई 15 दिनों में कर सकता है, B उसी काम का 75% 18 दिनों में और C उसी काम को 36 दिनों में कर सकता है। B और C एकसाथ 8 दिनों तक कार्य करते हैं। A अकेला शेष कार्य को कितने दिनों में पूरा करेगा?

  1. 25 days 25 दिन

  2. 20 days 20 दिन

  3. 12 days 12 दिन

  4. 6 days 6 दिन

  5. 18 days 18 दिन
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

A does 1/3 work in 15 days, so complete work in 45 days (rate = 1/45). B does 75% in 18 days, so complete work in 24 days (rate = 1/24). C does complete work in 36 days (rate = 1/36). B and C together for 8 days complete 8×(1/24 + 1/36) = 8×(3/72 + 2/72) = 8×5/72 = 40/72 = 5/9 of work. Remaining work = 4/9. A alone does 4/9 work at rate 1/45, so time = (4/9)/(1/45) = (4/9)×45 = 20 days.

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