Working 5 hours a day, A can Complete a work in 8 days and working 6 hours a day, B can complete the same work in 10 days. Working 8 hours a day, they can jointly complete the work in:
A. 3 days B. 4 days C. 4.5 days D. 5.4 days Answer: Option AShow Answer
Solution(By Apex Team)
1st Method:
Working 5 hours a day, A can complete the work in 8 days i.e.
= 5 × 8 = 40 hours
Working 6 hours a day, B can complete the work in 10 days i.e.
= 6 × 10 = 60 hours
(A + B)’s 1 hour’s work,
$\begin{array}{l}
=\frac{1}{40}+\frac{1}{60} \\
=\frac{3+2}{120} \\
=\frac{5}{120} \\
=\frac{1}{24}
\end{array}$
Hence, A and B can complete the work in 24 hours i.e. they require 3 days to complete the work.
2nd method % 1 hour’s work of A $=\frac{100}{40}=2.5 \%$ % 1 hour’s work of B $=\frac{100}{60}=1.66 \%$ (A + B) one hour’s % work, = (2.5 + 1.66) = 4.16% Time to complete the work, $=\frac{100}{4.16}=24 \text { hours }$ Then, $\frac{24}{8}=3 \text { days }$ They need 3 days, working 8 hours a day to complete the work.
2nd method % 1 hour’s work of A $=\frac{100}{40}=2.5 \%$ % 1 hour’s work of B $=\frac{100}{60}=1.66 \%$ (A + B) one hour’s % work, = (2.5 + 1.66) = 4.16% Time to complete the work, $=\frac{100}{4.16}=24 \text { hours }$ Then, $\frac{24}{8}=3 \text { days }$ They need 3 days, working 8 hours a day to complete the work.
