Examples(Set 1) - Time and Work

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

Answer: Option D

Explanation:
Amount of work Hithaishi can do in 1 day = 1/ 15
Amount of work Joey can do in 1 day = 1/ 20
Amount of work Hithaishi and Joey together can do in 1 day = 1/ 15 + 1/ 20
= 7/ 60
Amount of work Hithaishi and Joey together can do in 4 days = 4 × 7/ 60
= 7/ 15
Fraction of work left = 1 − 7/ 15
= 8/ 15






2.Nithesh can lay railway track between two stations in 16 days. Minati can do the same job in 12 days. With the help of Bhuvan, they completes the job in 4 days. How much days does it take for Bhuvan alone to complete the work?

A. 10 days
B. 9 and 1/5 days
C. 9 and 2/5 days
D. 9 and 3/5 days

Answer: Option D

Explanation:
Amount of work Nithesh can do in 1 day
= 1/ 16
Amount of work Minati can do in 1 day
= 1/ 12
Amount of work Nithesh, Minati and Bhuvan can together do in 1 day
= 1/ 4
Amount of work Bhuvan can do in 1 day
= 1/ 4 − ( 1/ 16 + 1/ 12 )
= 3/ 16 − 1 12
= 5/ 48
Hence Bhuvan can do the job on 48/ 5 days =
9and 3/5 days






3.Chandan, Puneeth and Shiv can do a work in 20 , 30 and 60 days respectively. How many days does it need to complete the work if Chandan does the work and he is assisted by Puneeth and Shiv on every third day?
A. 15 days
B. 9 days
C. 10 days
D. 14 days

Answer: Option A

Explanation:
Amount of work Chandan can do in 1 day = 1/ 20
Amount of work Puneeth can do in 1 day = 1/ 30
Amount of work Shiv can do in 1 day = 1/ 60
Chandan is working alone and every third day Puneeth and Shiv is helping him Work completed in every three days
= 3 × 1/ 20 + 1/ 30 + 1/ 60 = 1/ 5
So work completed in 15 days
= 5 × 1/ 5 = 1
That is, the work will be done in 15 days






4.Pavani is thrice as good as B in work. Pavani is able to finish a job in 60 days less than Chandler. They can finish the work in _ days if they work together.
A. 26 days
B. 18 days
C. 22and 1/2 days
D. 24 days

Answer: Option C

Explanation:
Let time taken by Pavani to complete the work = x days
so,time taken by Chandler to complete the work =3x
given: x=3x-60
x=30
time taken by Pavani to complete the work = 30days
time taken by Chandler to complete the work =3x= 90 days

Amount of work Pavani can do in 1 day =1/30
Amount of work Chandler can do in 1 day =1/90
Amount of work Pavani and Chandler can together do in 1 day =1/30+1/90
=2/45
time taken by Pavani and Chandler together to complete the work =45/2
=22 and 1/2 days







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

Answer: Option B

Explanation: Amount of work Vrushabh can do in 1 day = 1/ 6
Amount of work Rachel can do in 1 day = 1/ 8
Amount of work Vrushabh and Rachel together can do in 1 day
= 1/ 6 + 1/ 8 = 7/ 24
Amount of work Vrushabh, Rachel and Monica together did in one day = 1/ 3
Therefore, amount of work Monica can do in 1 day
= 1/ 3 − 7/ 24 = 1/ 24
Work Vrushabh can do in 1 day: work Rachel can do in 1 day: work Monica can do in 1 day = 1/ 6 : 1/ 8 : 1/ 24 = 4 : 3 : 1
Amount to be paid to Monica = 3200 × 1/ 8
= 400







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