RRB Junior Engineer Stage 1 Model Papers 1

$\left(\mathit{A}+\mathit{B}+\mathit{C}\right)$ 's 1 day's work $={\left(\frac{1}{40}\right)}^{\mathit{t}\mathit{h}}$ part of whole work
$\left(\mathit{A}+\mathit{B}+\mathit{C}\right)$ 's 16 days work $=\frac{16}{40}=\frac{2}{5}$ of whole work $\left(\mathit{B}+\mathit{C}\right)$ completes remaining work in 40 days $\left(\mathit{B}+\mathit{C}\right)$ completes ${\left(\frac{3}{5}\right)}^{\mathit{t}\mathit{h}}$ part of work in 40 days.
$\left(\mathit{B}+\mathit{C}\right)$ completes whole work in $\frac{40\times 5}{3}=\frac{200}{3}$ days
$\frac{1}{\mathit{A}}+\frac{1}{\mathit{B}}+\frac{1}{\mathit{C}}=\frac{1}{40}$
$\frac{1}{\mathit{A}}+\frac{3}{200}=\frac{1}{40}$
$\frac{1}{\mathit{A}}=\frac{1}{40}-\frac{3}{200}=\frac{5-3}{200}=\frac{2}{200}$
$\frac{1}{\mathit{A}}=\frac{1}{1000}$
A alone can complete whole work in 100 days