# Aptitude - Time and Work

### Exercise :: Time and Work - General Questions

16.

X and Y can do a piece of work in 20 days and 12 days respectively. X started the work alone and then after 4 days Y joined him till the completion of the work. How long did the work last?

 A. 6 days B. 10 days C. 15 days D. 20 days

Explanation:

 Work done by X in 4 days = 1 x 4 = 1 . 20 5

 Remaining work = 1 - 1 = 4 . 5 5

 (X + Y)'s 1 day's work = 1 + 1 = 8 = 2 . 20 12 60 15

 Now, 2 work is done by X and Y in 1 day. 15

 So, 4 work will be done by X and Y in 15 x 4 = 6 days. 5 2 5

Hence, total time taken = (6 + 4) days = 10 days.

17.

A is 30% more efficient than B. How much time will they, working together, take to complete a job which A alone could have done in 23 days?

A. 11 days
B. 13 days
C.

 20 3 days 17

D. None of these

Explanation:

Ratio of times taken by A and B = 100 : 130 = 10 : 13.

Suppose B takes x days to do the work.

 Then, 10 : 13 :: 23 : x x = 23 x 13  x = 299 . 10 10

 A's 1 day's work = 1 ; 23

 B's 1 day's work = 10 . 299

 (A + B)'s 1 day's work = 1 + 10 = 23 = 1 . 23 299 299 13

Therefore, A and B together can complete the work in 13 days.

18.

Ravi and Kumar are working on an assignment. Ravi takes 6 hours to type 32 pages on a computer, while Kumar takes 5 hours to type 40 pages. How much time will they take, working together on two different computers to type an assignment of 110 pages?

 A. 7 hours 30 minutes B. 8 hours C. 8 hours 15 minutes D. 8 hours 25 minutes

Explanation:

 Number of pages typed by Ravi in 1 hour = 32 = 16 . 6 3

 Number of pages typed by Kumar in 1 hour = 40 = 8. 5

 Number of pages typed by both in 1 hour = 16 + 8 = 40 . 3 3 Time taken by both to type 110 pages = 110 x 3 hours 40

 = 8 1 hours (or) 8 hours 15 minutes. 4

19.

A, B and C can complete a piece of work in 24, 6 and 12 days respectively. Working together, they will complete the same work in:

A.
 1 day 24
B.
 7 day 24
C.
 3 3 days 7
D. 4 days

Explanation:

 Formula: If A can do a piece of work in n days, then A's 1 day's work = 1 . n

 (A + B + C)'s 1 day's work = 1 + 1 + 1 = 7 . 24 6 12 24

 Formula: If A's 1 day's work = 1 , then A can finish the work in n days. n

 So, all the three together will complete the job in 24 days = 3 3 days. 7 7

20.

Sakshi can do a piece of work in 20 days. Tanya is 25% more efficient than Sakshi. The number of days taken by Tanya to do the same piece of work is:

 A. 15 B. 16 C. 18 D. 25

Explanation:

Ratio of times taken by Sakshi and Tanya = 125 : 100 = 5 : 4.

Suppose Tanya takes x days to do the work.

 5 : 4 :: 20 : x x = 4 x 20 5 x = 16 days.

Hence, Tanya takes 16 days to complete the work.