A and B can do a piece of work separately in 8 and 12 h. If they work alternate hours, A starting, when will the work be finished?

91/2 h
9 h
81/2 h
8 h

Correct Answer: 91/2 h

Explanation:

(A + B +)'s 2 h work = 1/8 + 1/12 = 5/24
(A + B)'s 8 h work = (5 x 8)/(24 x 2) = 5/6
Work done by A in 9th h = 1/8
Total work done upto 9th h = 5/6 + 1/8 = 23/24
Remaining wok = 1/24
B's 1 h work = 1/12
B can do 1/24 of the work = (1/24) x 12 = 1/2 h
So, both can finish the job in 9¹/₂ h.

← Previous Question Next Question→

More Questions from Time and Work

A contractor undertook to do a piece of work in 9 days. He employed a certain number of laborious but 6 of them being absent from the very first day, the rest could finish the work in 15 days. Find the number of men originally employed.
Two pipes A and B can each fill a tank in 40 and 60 min, respectively. There is an outlet C. If all the 3 pipes are opened up, the tank will be filled in 30 min. How much time will it take for C alone to empty the full tank?
A conveyer belt delivers baggage at the rate of 3 tonne in 5 min and a second conveyer belt delivers baggage at the rate of 1 tonne in 2 min. How much time will it take to get 33 tonne of baggage using both conveyer belts?
Rohit, Harsh and Sanjeev are three typists, who working simultaneously, can type 216 pages in four hours . In one hour, Sanjeev can type as many pages more than Harsh as Harsh can type more than Rohit. During a period of five hours, Sanjeev can type as many passages as Rohit can, during seven hours. How many pages does each of them type per hour?
A and B together can do a piece of work in 12 days which B and C together can do in 16 days. After A has been working at it for 5 days and B for 7 days, C takes up and finishes it alone in 13 days. In how many days, C alone can do the work?
A and B can complete a piece of work in 12 days while B and C in 15 days. A did the work for 3 days, B for 8 days and C for 10 days to complete the work. In how many days C alone can complete the work?
A supplies 20 men who work for 8 h per days for 6 days. B supplies 15 men working at 9 h per day for 7 day and C supplies 10 men working 6 h per day for 8 days to do a certain lob. If ₹ 636 is paid for all the labour, what is C's share?
A and B can do a piece of work in 45 days and 40 days, respectively. They began to do the work together but A left after some days and then B completed the remaining work in 23 days. The number of days after which A left the work, is?
50 men or 80 women can finish a job in 50 days. A contractor deploys 40 men and 48 women for this work but after every duration of 10 days, 5 men and 8 women are removed till the work is completed. The work is completed in?
A can do a piece of work in 10 days, B in 15 days. They work together for 5 days, the rest of the work is finished by C in two more days. If they get Rs 3000 as wages for the whole work, what are the daily wages of A, B and C respectively (in Rs )?

Discussion & Comments

No comments yet. Be the first to comment!

Join Discussion