Subject: General Aptitude · Chapter: Time and Work · Exam: · Marks: · Difficulty:
A is thrice as good a workman as B and so takes 60 days less than B for doing a job. The time in which they can do the job together is (A.A.O. Exam, 2010; M.A.T., 2010)
(a)22 days
(b)30 days
(c)45 days
(d)60 days
Answer
Answer (as printed): A
Explanation
Ratio of times taken by A and B = 1:3. If difference of time is 2 days, B takes 3 days. If difference of time is 60 days, B takes $\frac{3}{2} \times 60 = 90$ days. So, A takes 30 days to do the work. A's 1 day's work $=\frac{1}{30}$; B's 1 day's work $=\frac{1}{90}$. (A+B)'s 1 day's work $=\left(\frac{1}{30}+\frac{1}{90}\right)=\frac{4}{90}=\frac{2}{45}$. $\therefore$ A and B together can do the work in $\frac{45}{2}=22\frac{1}{2}$ days.
Explanation as extracted from the printed page; notation may be imperfect.