If two persons A and B works 7 hours a day, then A and B alone can complete a piece of work in 6 days and 8 days respectively. While working 8 hours a day, in what time they would complete it together?
If two persons A and B works 7 hours a day, then A and B alone can complete a piece of work in 6 days and 8 days respectively. While working 8 hours a day, in what time they would complete it together?
[A]2.5 days
[B]3 days
[C]4 days
[D]3.6 days
3 days
A alone can complete the work in 42 days working 1 hour daily. Similiarly, B will take 56 days working 1 hour daily.
A’s 1 day’s work $latex = \frac{1}{42}&s=1$
B’s 1 day’s work $latex = \frac{1}{56}&s=1$
(A + B)’s 1 day’s work $latex = \frac{1}{42}+\frac{1}{56} = \frac{4+3}{168} = \frac{7}{168}&s=1$
∴ Time taken by (A + B) working 8 hours daily $latex = \frac{168}{7\times 8} =&s=1$ 3 days
Hence option [B] is correct answer.