Question

A can lay a railway track between two given stations in 16 days and B can do the same job in 12 days. With the help of C, they did the job in 4 days only. Then, C alone can do the job in how many days?

• A. 46/5 days
• B. 47/5 days
• C. 48/5 days
• D. 10 days
• E. 7 days

Answer 1

The correct option is C

48/5 days

(A+B+C)’s 1 day’s work = $\frac{1}{4}$, A’s 1 day’s work = $\frac{1}{16}$, B’s 1 day’s work = $\frac{1}{12}$

∴ C’s 1 day’s work = $(\frac{1}{16}+\frac{1}{12})=(\frac{1}{4}-\frac{7}{48})=\frac{5}{48}$

So, C alone can do the work in $\frac{48}{5}=9\frac{3}{5}$ days