Subject: General Aptitude · Chapter: Time and Work · Exam: · Marks: · Difficulty:
A, B and C together can complete a piece of work in 10 days. All the three started working at it together and after 4 days A left. Then B and C together completed the work in 10 more days. A alone could complete the work in :
(a)15 days
(b)16 days
(c)25 days
(d)50 days
Answer
Answer (as printed): C
Explanation
Work done by A, B and C in 4 days $=\left(\frac{1}{10} \times 4\right)=\frac{2}{5}$. Remaining work $=\left(1-\frac{2}{5}\right)=\frac{3}{5}$. Now, $\frac{3}{5}$ work is done by B and C in 10 days. Whole work will be done by B and C in $\left(10 \times \frac{5}{3}\right)=\frac{50}{3}$ days. (A+B+C)'s 1 day's work $=\frac{1}{10}$, (B+C)'s 1 day's work $=\frac{3}{50}$. A's 1 day's work $=\left(\frac{1}{10}-\frac{3}{50}\right)=\frac{2}{50}=\frac{1}{25}$. $\therefore$ A alone could complete the work in 25 days.
Explanation as extracted from the printed page; notation may be imperfect.