46. A does a work in 10 days and B does the same work in 15 days. In how many days they together will do the same work?

A. 5 days B. 6 days C. 8 days D. 9 days

Answer Answer: Option B Explanation: A's 1 day's work = 1/10 and B's 1 day's work = 1/15.
therefore (A+B)'s 1 day's work =( 1/10+ 1/15)= 1/6.
so, both together will finish the work in 6 days.

47. A and B working separately can do a piece of work in 9 and 12 days respectively. If they work for a day alternately, A beginning, in how many days, the work will be completed?

A. 7 1/3 days B. 8 1/5 days C. 10 1/4 days D. 5 1/2 days

Answer Answer: Option C Explanation: (A+B)'s 2 days' work = (1/9+1/12)= 7/36.
work done in 5 pairs of days = (5*7/36) = 35/36.
remaining work = (1- 35/36) = 1/36.
on 11th day, it is A's turn. 1/9 work is done by him in 1 day.
1/36 work is done by him in (9*1/36) = 1/4 day.
therefore total time taken = ( 10 + 1/4) days = 10 1/4 days.

48. A can do a work in 7 days of 9 hours each and B can do it in 6 days of 7 hours each. How long will they take to do it working together 8 2/5 hours a day?

A. 3 days B. 4 days C. 6 days D. 2 days

Answer Answer: Option A Explanation: A can complete the work in = ( 7*9) = 63 hours
B can complete the work in = ( 6*7) = 42 hours
A's 1 hour's work = 1/63 and B's 1 hour's work = 1/42
(A + B)'s 1 hour's work = (1/63 + 1/42) = 5/126 = Number of days of 8 2/5 hours each = (126/5 * 5/42) = 3 days

49. A & B together can complete a piece of work in 4 days. If A alone can complete the same work in 12 days in how many days can B alone complete that work?

A. 7 days B. 5 days C. 6 days D. 9 days

Answer Answer: Option C Explanation: (A + B)'s 1 day's work = 1/4; A's 1 day's work = 1/12;
B's 1 day's work = (1/4 - 1/12) = 1/6
Hence B alone can complete the work in 6 days.

50. Worker A takes 8 Hours to do a job. Worker B Takes 10 Hours to do the same job. How long should it take both A & B working together but independently to do the Same Job?

A. 32/9 B. 40/9 C. 35/8 D. 30/5

Answer Answer: Option B Explanation: A's 1 Hour work=1/8, B's 1hour work =1/10
(A+B)'s 1 hour work =(1/8+1/10)=9/40.
Both A & B Complete the work in 40/9 days