Multiple choice

A and B together can do a piece of work in 12 days, which B and C together can do in 16 days. After A has been working at it for 5 days and B for 7 days, C finishes it in 13 days. In how many days C alone will do the work? A और B एक साथ एक कार्य को 12 दिनों में कर सकते हैं, जिसे B और C मिलकर 16 दिनों में कर सकते हैं। A द्वारा उस पर 5 दिनों तक और B द्वारा 7 दिनों तक काम करने के बाद, C उसे 13 दिनों में पूरा करता है। C अकेले उस कार्य को कितने दिनों में करेगा?

  1. 22 days 22 दिन

  2. 24 days 24 दिन

  3. 20 days 20 दिन

  4. 25 days 25 दिन

  5. None of these इनमें से कोई नहीं
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

A + B = 1/12 work/day, B + C = 1/16 work/day. Work done: A worked 5 days, B worked 7 days, C worked 13 days. So 5A + 7B + 13C = 1 (complete work). Substituting A = 1/12 - B and C = 1/16 - B: 5(1/12 - B) + 7B + 13(1/16 - B) = 1. Solving: 5/12 + 13/16 + (7 - 5 - 13)B = 1. This gives -11B = 1 - 5/12 - 13/16 = -11/48, so B = 1/48. Then C = 1/16 - 1/48 = 1/24. So C alone takes 24 days.

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