1. A, B and C can do a piece of work in 20, 30 and 60 days respectively. In how many days can A do the work if he is assisted by B and C on every third day?
A. 12
B. 15
C. 16
D. 18
Answer Option B
Explanation:
A's 2 day's work =(1/20 *2) = 1/10
Work done in 3 days =(1/10 + 1/10 ) = 1/5
Whole work will be done in (3 x 5) = 15 days.
2.A can do a piece of work in 4 hours; B and C together can do it in 3 hours, while A and C together can do it in 2 hours. How long will B alone take to do it?
A. 8
B. 10
C. 12
D. 24
Answer Option C
Explanation:
A's 1 hour's work = 1/4
(A + B + C)'s 1 hour's work =(1/4 + 1/3 ) = 7/12
B alone will take 12 hours to do the work.
3.
A can do a certain work in the same time in which B and C together can do it. If A and B together could do it in 10 days and C alone in 50 days, then B alone could do it in:
A. 15
B. 20
C. 25
D. 30
Answer Option A
Explanation:
(A + B)'s 1 day's work =1/10
C's 1 day's work = 1/10
A's 1 day's work = (B + C)'s 1 day's work
A's 1 day's work = 3/50
So, B alone could do the work in 25 days.