SSC CGL Tier II 1 Dec 2016 Paper 1

(4) According to the question,
John does $\frac{1}{2}$ work in 3 hours.
∴ Time taken by John in doing whole work = 6 hours
Joe does $\frac{1}{8}$ work in 1 hour.
∴ Time taken by Joe in doing whole work = 8 hours
Remaining work = $\frac{1}{2}-\frac{1}{8}$ $=\frac{4-1}{8}=\frac{3}{8}$ parts
$\therefore$ Time taken by George $=\frac{8\times 5}{3}=\frac{40}{3}$ hours
Work done by all three in 1 hour =$\frac{1}{6}+\frac{1}{8}+\frac{3}{40}$ $=\frac{20+15+9}{120}=\frac{44}{120}$ $=\frac{11}{30}$
$\therefore$ Required time $=\frac{30}{11}$ $=2\frac{8}{11}$ hours