Subject: General Aptitude · Chapter: Time and Work · Exam: · Marks: · Difficulty:
A is 30\% more efficient than B. How much time will they, working together, take to complete a job which A alone could have done in 23 days ?
(a)11 days
(b)13 days
(c)$20 \frac{3}{17}$ days
(d)None of these
Answer
Answer (as printed): B
Explanation
Ratio of times taken by A and B = $100:130=10:13$. Suppose B takes $x$ days to do the work. Then, $10:13::23:x \Rightarrow x=\frac{23 \times 13}{10}=\frac{299}{10}$. A's 1 day's work $=\frac{1}{23}$; B's 1 day's work $=\frac{10}{299}$. (A+B)'s 1 day's work $=\left(\frac{1}{23}+\frac{10}{299}\right)=\frac{23}{299}=\frac{1}{13}$. $\therefore$ A and B together can complete the job in 13 days.
Explanation as extracted from the printed page; notation may be imperfect.