Subject: General Aptitude · Chapter: Time and Work · Exam: · Marks: · Difficulty:
A and B can do a piece of work in 28 and 35 days respectively. They began to work together but A leaves after some time and B completed the remaining work in 17 days. After how many days did A leave?
(a)$7 \frac{5}{9}$ days
(b)8 days
(c)9 days
(d)$14 \frac{2}{5}$ days
Answer
Answer (as printed): B
Explanation
(A+B)'s 1 day's work $=\left(\frac{1}{28}+\frac{1}{35}\right)=\frac{9}{140}$. Work done by B in 17 days $=\left(\frac{1}{35} \times 17\right)=\frac{17}{35}$. Remaining work $=\left(1-\frac{17}{35}\right)=\frac{18}{35}$. Now, $\frac{9}{140}$ work was done by (A+B) in 1 day. So, $\frac{18}{35}$ work was done by (A+B) in $\left(\frac{18}{35} \times \frac{140}{9}\right)=8$ days. $\therefore$ A left after 8 days.
Explanation as extracted from the printed page; notation may be imperfect.