RRB RPF RPSF SI and CONS Model Papers 8 with solutions

(3) A + B – 72 days 1 work
∴ A + B in 1 day $\frac{1}{72}$ work
Similarly,
B + C in 1 day $\frac{1}{120}$ work
and A + C in 1 day $\frac{1}{90}$ work
∴ 2 (A + B + C) 1 day
$\frac{1}{72}+\frac{1}{120}+\frac{1}{90}$
A + B + C in 1 day
$\frac{1}{2}\left(\frac{1}{72}+\frac{1}{120}+\mathrm{}\frac{1}{90}\right)$
$=\frac{1}{20}\left(\mathrm{}\frac{10+6+8}{720}\right)$
$=\frac{1}{2}\times 24720=\frac{1}{60}$work
A + B + C = $\frac{1}{60}$ work 1 day
A + B + C = 1 work = 60 days