RRB RPF RPSF SI and CONS Model Papers 8 with solutions

(4) ∵ A in 12 days can do 1 work
∴ A in 1 day can do $\frac{1}{12}$ work
A in 2 days can do $\frac{2}{12}$ =$\frac{1}{6}$ work
B in 18 days can do 1 work
∴ B in 1 day can do $\frac{1}{18}$ work
B in 2 days can do $\frac{1}{9}$ work
∴ Total work in two days $=\frac{1}{6}+\frac{1}{9}=\frac{3+2}{18}=\frac{5}{18}$ work
Hence, the remaining work $=1-\frac{5}{18}=\frac{13}{18}$ work
∵ B 1 work in 18 days
∴ $\mathrm{B}\frac{13}{18}$ work $\frac{13}{18}\times 18$ = 13 days