Aptitude - Time and Work - Discussion
Discussion Forum : Time and Work - General Questions (Q.No. 3)
3.
A, B and C can do a piece of work in 20, 30 and 60 days respectively. In how many days can A do the work if he is assisted by B and C on every third day?
Answer: Option
Explanation:
| A's 2 day's work = |  |
1 | x 2 |  |
= | 1 | . |
| 20 | 10 |
| (A + B + C)'s 1 day's work = | |
1 | + | 1 | + | 1 | |
= | 6 | = | 1 | . |
| 20 | 30 | 60 | 60 | 10 |
| Work done in 3 days = | |
1 | + | 1 | |
= | 1 | . |
| 10 | 10 | 5 |
| Now, | 1 | work is done in 3 days. |
| 5 |
Whole work will be done in (3 x 5) = 15 days.
Discussion:
357 comments Page 19 of 36.
Deepti said:
1 decade ago
Its written every 3rd day NOT First 3 days. Therefore the answer is as below:
(A+B+C)'s 1 day work = (1/20 + 1/30 + 1/60) = 1/10.
=> They all take 10 days to complete their work together.
Out of those 10 days, 3th, 6th and 9th are the 3rd days. In total B and C can help A for only 3 days.
Therefore, (A's 1 days work) + (B+C) 1 day work*3 = 1/20 + (1/30+1/60) *3 = 4/20 = 1/5.
If 1/5 is the work in 3 days, Then complete work done = 5*3 = 15.
Ans: 15 days.
(A+B+C)'s 1 day work = (1/20 + 1/30 + 1/60) = 1/10.
=> They all take 10 days to complete their work together.
Out of those 10 days, 3th, 6th and 9th are the 3rd days. In total B and C can help A for only 3 days.
Therefore, (A's 1 days work) + (B+C) 1 day work*3 = 1/20 + (1/30+1/60) *3 = 4/20 = 1/5.
If 1/5 is the work in 3 days, Then complete work done = 5*3 = 15.
Ans: 15 days.
Nandha said:
1 decade ago
@Ajit.
A do a work two days independently, so (1/20+1/20) = 1/10 instead of they taken (1/20*2).
A do a work two days independently, so (1/20+1/20) = 1/10 instead of they taken (1/20*2).
Ranju said:
1 decade ago
(A+B+C)'s 1 day of work is (1/20+1/30+1/60) = 1/10.
A's 2 days of work is (1/20 X 2) = 1/10.
As on the third day A is assisted by B and C.
=> A's 2 days of work + On 3rd day A is assisted by B and C i.e. (A+B+C) 's 1 day of work.
1/10 + 1/10 = 2/10 = 1/5.
As 1/5 part of work is done in 3 days.
Therefore 1 part of work is done in 3 X 5 = 15 days.
A's 2 days of work is (1/20 X 2) = 1/10.
As on the third day A is assisted by B and C.
=> A's 2 days of work + On 3rd day A is assisted by B and C i.e. (A+B+C) 's 1 day of work.
1/10 + 1/10 = 2/10 = 1/5.
As 1/5 part of work is done in 3 days.
Therefore 1 part of work is done in 3 X 5 = 15 days.
Garima Yadav said:
1 decade ago
I haven't got it. Can anyone please help me for this?
Ashwini said:
1 decade ago
Can you explain how 6/60 came?
Sindhu said:
1 decade ago
@Ashwini.
As they mentioned in the question A is assisted B and C on every third day means on every third day A B C do the work together. That means you have to add A B C 's one day work.
i.e 1/20+1/30+1/60 = 6/60 = 1/10.
As they mentioned in the question A is assisted B and C on every third day means on every third day A B C do the work together. That means you have to add A B C 's one day work.
i.e 1/20+1/30+1/60 = 6/60 = 1/10.
Animesh said:
1 decade ago
A 20--------------------3.
B 30 ---LCM 60 -------2.
C 60--------------------1.
Total = 3+2+1 = 6.
So answer = 60/6 = 10.
B 30 ---LCM 60 -------2.
C 60--------------------1.
Total = 3+2+1 = 6.
So answer = 60/6 = 10.
Trinadh said:
1 decade ago
1/20, 1/30, 1/60.
Add 1/3 to the ends of both B and C.
= 1/20+1/30*3+*1/60*3.
= 1/15.
Add 1/3 to the ends of both B and C.
= 1/20+1/30*3+*1/60*3.
= 1/15.
Ram said:
1 decade ago
Last step:
1/5 work = 3 days.
W/5 = 3d.
W = 3*5d.
W = 15d.
Full work = 15 days.
1/5 work = 3 days.
W/5 = 3d.
W = 3*5d.
W = 15d.
Full work = 15 days.
A govardhan reddy said:
1 decade ago
A can do 20 days so = 1/20.
A can do with B and C every third day = 20/3 = 18+2 (alone).
A+B+C = (3/18+1/30+1/60) = 1/5.
So the A work done in three days = 5*3 = 15 days.
A can do with B and C every third day = 20/3 = 18+2 (alone).
A+B+C = (3/18+1/30+1/60) = 1/5.
So the A work done in three days = 5*3 = 15 days.
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