We use cookies to personalise content and ads, to provide social media features and to analyse our traffic. We also share information about your use of our site with our social media, advertising and analytics partners.More informationAgree
menu ×
Google
Custom Search
cancel
search
FacebookTwitterLinkedIn×
share
page location
×
ad

Solved Examples(Set 1) - Time and Work

1. P is able to do a piece of work in 15 days and Q can do the same work in 20 days. If they can work together for 4 days, what is the fraction of work left?
A. 7/15B. 11/15
C. 2/11D. 8/15
Discuss
answer with explanation

Answer: Option D

Explanation:

Amount of work P can do in 1 day = 1/15
Amount of work Q can do in 1 day = 1/20

Amount of work P and Q can do in 1 day = 1/15 + 1/20 = 7/60

Amount of work P and Q can together do in 4 days = 4 × (7/60) = 7/15

Fraction of work left = 1 - 7/15= 8/15

2. P can lay railway track between two stations in 16 days. Q can do the same job in 12 days. With the help of R, they completes the job in 4 days. How much days does it take for R alone to complete the work?
A. 9(1/5) daysB. 9(3/5) days
C. 9(2/5) daysD. 10 days
Discuss
answer with explanation

Answer: Option B

Explanation:

Amount of work P can do in 1 day = 1/16
Amount of work Q can do in 1 day = 1/12

Amount of work P, Q and R can together do in 1 day = 1/4

Amount of work R can do in 1 day = 1/4 - (1/16 + 1/12) = 3/16 - 1/12 = 5/48

=> Hence R can do the job on 48/5 days = 9 (3/5) days

3. P, Q and R can do a work in 20, 30 and 60 days respectively. How many days does it need to complete the work if P does the work and he is assisted by Q and R on every third day?
A. 15 daysB. 9 days
C. 10 daysD. 14 days
Discuss
answer with explanation

Answer: Option A

Explanation:

Amount of work P can do in 1 day = 1/20
Amount of work Q can do in 1 day = 1/30
Amount of work R can do in 1 day = 1/60

P is working alone and every third day Q and R is helping him

Work completed in every three days = 2 × (1/20) + (1/20 + 1/30 + 1/60) = 1/5

So work completed in 15 days = 5 × 1/5 = 1

Ie, the work will be done in 15 days

4. A is thrice as good as B in work. A is able to finish a job in 60 days less than B. They can finish the work in - days if they work together.
A. 22 ½ daysB. 18 days
C. 26 daysD. 24 days
Discuss
answer with explanation

Answer: Option A

Explanation:

If A completes a work in 1 day, B completes the same work in 3 days

Hence, if the difference is 2 days, B can complete the work in 3 days

=> if the difference is 60 days, B can complete the work in 90 days

=> Amount of work B can do in 1 day= 1/90

Amount of work A can do in 1 day = 3 × (1/90) = 1/30

Amount of work A and B can together do in 1 day = 1/90 + 1/30 = 4/90 = 2/45

=> A and B together can do the work in 45/2 days = 22 ½ days

5. A can do a particular work in 6 days . B can do the same work in 8 days. A and B signed to do it for Rs. 3200. They completed the work in 3 days with the help of C. How much is to be paid to C?
A. Rs. 600B. Rs. 420
C. Rs. 400D. Rs. 380
Discuss
answer with explanation

Answer: Option C

Explanation:

Amount of work A can do in 1 day = 1/6
Amount of work B can do in 1 day = 1/8

Amount of work A + B can do in 1 day = 1/6 + 1/8 = 7/24

Amount of work A + B + C can do = 1/3

Amount of work C can do in 1 day = 1/3 - 7/24 = 1/24

work A can do in 1 day: work B can do in 1 day: work C can do in 1 day
= 1/6 : 1/8 : 1/24 = 4 : 3 : 1

Amount to be paid to C = 3200 × (1/8) = 400

Comments(184)

profileAnil Peshin
2015-06-26 14:28:14 
In Question no.7, you should ask in how many HOURS will B complete the work, not in how many DAYS because the answer is in Hours (12) not in days. Please slightly modify the statement, if correct
like 0 dislike 0 reply
profileSupport Team, careerbless.com
2015-06-27 17:37:01 
Thanks Mr.Anil Peshin for pointing this out. It is corrected.
like 0 dislike 0
profilevarsha sharma
2015-04-07 18:20:54 
A and B can complete their work in 5 days..A use his double efficiency and B use his half efficiency and complete their work in 4 days..in how many days A alone complete the work
like 0 dislike 0 reply
profileDev
2015-04-08 20:55:48 
Let work done by A in 1 day = a  (when working in normal efficiency)
and work done by B in 1 day = b (when working in normal efficiency)
Work done by A  and B in 1 day = 1/5
a + b = 1/5 ----(1)

Work done by A in 1 day (in double efficiency) = 2a
Work done by B in 1 day (in half efficiency) = b/2
Work done by A and B in 1 day (A in double efficiency and B in half efficiency) = 1/4
2a + b/2 = 1/4
8a + 2b = 1 ----(2)

Solving (1) and (2)
from (1) 2a + 2b = 2/5 ----(3)
(2)-(3) : 6a = 3/5
a = 3/30 = 1/10

Work done by A in 1 day = 1/10 (when working in normal efficiency)
A alone complete the work in 10 days when working in normal efficiency.
like 0 dislike 0
profileAnup
2015-04-02 14:35:05 
A can do a piece of work in 14 days which B can do in 21 days .They begin together but 3 days before COMPLETION of the work ,A leaves off. In how many days B will complete remaining work??
like 0 dislike 0 reply
profileDev
2015-04-08 18:06:06 
I think question is wrong. 3 days before COMPLETION of the work ,A leaves off. i.e., work will be completed in 3 days after A leaves?

Probably question is to find out the total number of days in which the work will get completed

Work done by A in 1 day = 1/14
Work done by B in 1 day = 1/21
Work done by A&B in 1 day = 1/14 + 1/21 = 5/42
B works alone in the last 3 days and completes 3*1/21 = 1/7 of the work.
Remaining work = 1 - 1/7 = 6/7
Time taken by A&B to do this 6/7 of the work = (6/7)/(5/42) = 36/5 = 7.2
Total days needed to complete the work =  7.2+3=10.2 days
like 0 dislike 0
profileazhar
2015-11-25 06:38:45 
in the above problem the question is asking about time taken by B to complete remaining work not about total time required...
like 0 dislike 0
profilesam
2015-12-23 11:40:48 
@azhar, time taken by B to complete remaining work is 3 days which is given in the question, isn't it?
like 0 dislike 0
profileamit
2015-04-01 09:36:17 
20 men can complete a task in 40 days. If after every five days two men left. In how many days the work will be completed?
like 0 dislike 0 reply
profileVishal Bhatnagar
2016-08-14 12:22:57 
20*40 = 800
So
20*5 = 100, 18*5= 90, 16*5 = 80, 14*5 =70, 12*5 = 60, 10*5 = 50, 8*5 = 40, 6*5 = 30, 4*5 = 20, 2*5=10
Total 100+90+80+70+60+50+40+30+20+10 = 550 & still 250 work is incompleted so no worker no work.
like 0 dislike 0
1234
...
19Next
1-10 of 184 comments

Add Your Comment

(use Q&A for new questions)
?
Name
cancel
preview