# Examples(Set 2) - Time and Work

6. men and women can complete a work in days. men and 60 women can complete a work in 3 days. men and women can do the same work in:

A. 10 days

B. 12 days

C. 8 days

D. 2 days

Explanation:

7. P can do a work in the same time in which Q and R together can do it. If P and Q work together, the work can be completed in 10days. R alone needs 50 days to complete the same work. then Q alone can do it in:

A. 30 days

B. 20 days

C. 25 days

D. 15 days

Explanation:

Amount of work P can do in 1 day = 1/ P

Amount of work Q can do in 1 day = 1/Q

Amount of work R, can do in 1 day = 1/ 50

Amount of work P and Q can do in 1 day

= 1/P+1/Q =1/10

given: 1/P=1/Q+1/50 (P can do a work in the same time in which Q and R together can do it)

solving both equations

1/Q=1/25

Q=25 days

8.A can do a piece of work in
6
hours. A and C together can do it in just
3
hours, while B and C together need
2
hours to finish the same work. B alone can complete the work in:

A.
6
hours

B.
3
hours

C.
5
hours

D.
2
hours

Explanation:

Amount of work A can do in 1 hour

1/A= 1/6

Amount of work A and C can do together in 1 hour

1/A+1/C= 1/3

Amount of work B and C can do together in 1 hour

1/B+1/C= 1/2

solving above equations

1/B=1/3

B=3

B alone will take 3 hours

9.A completes
80
%
of a work in
20
days. Then B also joins and A and B together finish the remaining work in
3
days. How long does it need for B if he alone completes the work?

A.
31
days

B.
22
days

C.
26
days

D.
37 and
1
2
days

Explanation:

Work done by A in 20 days

= 80/ 100

= 4/ 5

Work done by A in 1 day

= ( 4/ 5 )/ 20

= 1/ 25

Work done by A and B in 3 days

= 20/ 100

= 1/ 5 (because remaining 20 % is done in 3 days by A and B)

Work done by A and B in 1 day = (1/ 5)/3

=1/15

Work done by B in 1 day

= 1/ 15 − 1/ 25 = 2/ 75

Therefore, B can complete the work in 75/ 2 days

= 37 and 1/ 2 days

10.Machine P can print one lakh books in
8
hours. Machine Q can print the same number of books in
10
hours while machine R can print the same in
12
hours. All the machines started printing at
9
a.m. Machine P is stopped at
11
a.m. and the remaining two machines complete work. Approximately at what time will the printing of one lakh books be completed?

A.
11
a.m.

B.
3
p.m.

C.
1
p.m.

D.
2
p.m.

Explanation: Work done by P in 1hour =1/8

Work done by Q in 1hour = 1/10

Work done by R in 1hour =1/12

P worked for 2 hrs = 2*1/8

suppose Q and R worked for 'x' hrs then,

2*1/8+(1/10)*x+(1/12)x = 1

x=4.09

9+4.09 = 1pm