A and B can do a piece of work in 10 days. B and C can do it in 12 days. A and C can do it in 15 days. How long will A take to do it alone?
A and B can do a piece of work in 10 days. B and C can do it in 12 days. A and C can do it in 15 days. How long will A take to do it alone?
[A]20 days
[B]24 days
[C]30 days
[D]40 days
24 days
(A + B)’s 1 day’s work $latex = \frac{1}{10}&s=1$
(B + C)’s 1 day’s work $latex = \frac{1}{12}&s=1$
(C + A)’s 1 day’s work $latex = \frac{1}{15}&s=1$
On adding,
2(A + B + C)’s 1 day’s work $latex = \frac{1}{10}+\frac{1}{12}+\frac{1}{15} = \frac{6+5+4}{60} = \frac{1}{4}&s=1$
∴ (A + B + C)’s 1 day’s work $latex = \frac{1}{8}&s=1$
∴ A’s 1 day’s work $latex = \frac{1}{8}-\frac{1}{12} = \frac{3-2}{24} = \frac{1}{24}&s=1$
∴ A alone will complete the work in 24 days.
Hence option [B] is correct answer.
3 Comments
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Ren
May 22, 2018 at 10:04 am∴ (A + B + C)’s 1 day’s work =1/8
How is this possible??
Me
August 17, 2018 at 6:41 pmyou divide 1/4 by 2
Maya jain
November 9, 2018 at 5:04 pm2( A+ B+ C)= 1/4 then (A+ B+ C) = 1/4*2 =1/8.
So, the answer becomes (A+B+C) = 1/8