A, B and C working alone can complete a work in 14, 21 and 42 days respectively. In how many days A, B and C together can complete the same work?
Show answer & explanation
Correct answer: A
Explanation
A's work in 1 day = 1/14
B's work in 1 day = 1/21
C's work in 1 day = 1/42
Total work = 1/14 + 1/21 + 1/42
= 3/42 + 2/42 + 1/42
= 6/42
= 1/7
Time = 7 days