Subject: General Aptitude · Chapter: Time and Work · Exam: · Marks: · Difficulty:
A and B can do a piece of work in 5 days; B and C can do it in 7 days; A and C can do it in 4 days. Who among these will take the least time if put to do it alone?
(a)A
(b)B
(c)C
(d)Data inadequate
Answer
Answer (as printed): A
Explanation
(A + B)’s 1 day’s work = ; 5 1 (B + C)’s 1 day’s work = ; 7 1 (A + C)’s 1 day’s work = . 4 Adding, we get : 2 (A + B + C)’s 1 day’s work 1 1 1 83 = + + = . 5 7 4 140 83 (A + B + C)’s 1 day’s work = . 280 83 1 43 A’s 1 day’s work = − = ; 280 7 280 83 1 13 B’s 1 day’s work = − = ; 280 4 280 83 1 27 C’s 1 day’s work = − = . 280 5 280 280 280 280 Thus time taken by A, B, C is days, days, day 43 13 27 respectively. Clearly, the time taken by A is least. 1
Explanation as extracted from the printed page; notation may be imperfect.