Discussion

1) X,y,z complete a given work in 12 , 42 and 28 days respectively. if all three of them work together, in how many days the work will get completed ?

A) 41 days

B) 8 days

C) 44 days

D) 7 days

Suggestion

Explanation:

X's 1 day work = 1/12
Y's 1 day work = 1/42
Z's 1 day work = 1/28
All three are working together
X+Y+Z 's1 day work = (1/12) + (1/42) + (1/28)
[L C M of 12 , 42 , 28 = 84]
= (7 + 2 + 3) / 84 = 12 / 84
X+Y+Z 's 1 day work = 1/7
X+Y+Z will take 7 days to finish the work
Answer is 7