Aptitude - Time and Work

11. 

A can finish a work in 18 days and B can do the same work in 15 days. B worked for 10 days and left the job. In how many days, A alone can finish the remaining work?

A. 5
B.

5 1
2

C. 6
D. 8

Answer: Option C

Explanation:

B's 10 day's work = ( 1 x 10 ) = 2 .
15 3

Remaining work = ( 1 - 2 ) = 1 .
3 3

Now, 1 work is done by A in 1 day.
18

Therefore 1 work is done by A in ( 18 x 1 ) = 6 days.
3 3


12. 

4 men and 6 women can complete a work in 8 days, while 3 men and 7 women can complete it in 10 days. In how many days will 10 women complete it?

A. 35
B. 40
C. 45
D. 50

Answer: Option B

Explanation:

Let 1 man's 1 day's work = x and 1 woman's 1 day's work = y.

Then, 4x + 6y = 1 and 3x + 7y = 1 .
8 10

Solving the two equations, we get: x = 11 , y = 1
400 400

1 woman's 1 day's work = 1 .
400

10 women's 1 day's work = 1 x 10 = 1 .
400 40

Hence, 10 women will complete the work in 40 days.


13. 

A and B can together finish a work 30 days. They worked together for 20 days and then B left. After another 20 days, A finished the remaining work. In how many days A alone can finish the work?

A. 40
B. 50
C. 54
D. 60

Answer: Option D

Explanation:

(A + B)'s 20 day's work = ( 1 x 20 ) = 2 .
30 3

Remaining work = ( 1 - 2 ) = 1 .
3 3

Now, 1 work is done by A in 20 days.
3

Therefore, the whole work will be done by A in (20 x 3) = 60 days.


14. 

P can complete a work in 12 days working 8 hours a day. Q can complete the same work in 8 days working 10 hours a day. If both P and Q work together, working 8 hours a day, in how many days can they complete the work?

A.
5 5
11
B.
5 6
11
C.
6 5
11
D.
6 6
11

Answer: Option A

Explanation:

P can complete the work in (12 x 8) hrs. = 96 hrs.

Q can complete the work in (8 x 10) hrs. = 80 hrs.

P's1 hour's work = 1 and Q's 1 hour's work = 1 .
96 80

(P + Q)'s 1 hour's work = 1 + 1 = 11 .
96 80 480

So, both P and Q will finish the work in 480 hrs.
11

Number of days of 8 hours each = 480 x 1 = 60 days = 5 5 days.
11 8 11 11


15. 

10 women can complete a work in 7 days and 10 children take 14 days to complete the work. How many days will 5 women and 10 children take to complete the work?

A. 3
B. 5
C. 7
D. Cannot be determined
E. None of these

Answer: Option C

Explanation:

1 woman's 1 day's work = 1
70

1 child's 1 day's work = 1
140

(5 women + 10 children)'s day's work = 5 + 10 = 1 + 1 = 1
70 140 14 14 7

5 women and 10 children will complete the work in 7 days.