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 21 of 36.
Raman said:
1 decade ago
"A" can complete work in 20 days.
A's 1 day work is 1/20.
A's 2 days work is 2/20.
A's first day + A's second day + (A + B + C).
=> 1/20+1/20/+ (1/20+1/30+1/60).
=>2/20+ (1/20+1/30+1/60).
=>2/20+1/10 = 1/5.
So 3 days work = 1/5 convert it to one day work.
3/1/5 = 5/1*3 = 5*3 = 15 days.
Other way:
= 1/5 in three days we want to finish work.
= 1/5 + 1/5 + 1/5 + 1/5 + 1/5 = 5/5 = work finished.
A's 1 day work is 1/20.
A's 2 days work is 2/20.
A's first day + A's second day + (A + B + C).
=> 1/20+1/20/+ (1/20+1/30+1/60).
=>2/20+ (1/20+1/30+1/60).
=>2/20+1/10 = 1/5.
So 3 days work = 1/5 convert it to one day work.
3/1/5 = 5/1*3 = 5*3 = 15 days.
Other way:
= 1/5 in three days we want to finish work.
= 1/5 + 1/5 + 1/5 + 1/5 + 1/5 = 5/5 = work finished.
Sunil said:
1 decade ago
@Nikita answer is fantastic.
Farha said:
1 decade ago
The question is not about to ask the work of 3 days. Then why we are finding 3 days's work.
Can anybody explain, I am so confused.
Can anybody explain, I am so confused.
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.
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.
Veda said:
1 decade ago
"A" can complete work in 20 days.
A's 1 day work is 1/20.
A's 2 days work is 2/20.
According to the question A work for 2 day's and on the third day.
B & C assists (**helps, not replaced).
So it goes like this.
A's first day + A's second day + (A + B + C) on third day, B & C helped.
i.e 2 1/20+1/20/+(1/20+1/30+1/60).
=>2/20+(1/20+1/30+1/60).
=>2/20+1/10.
= 1/5.
So for first 2 days and combining B and C on third day they will work 1/5th of a work.
All together (A+A+ (A+B+C) ) works for 3 days to get 1/5th of a work so.
If 1/n work is done in 1 days total work is done in 1*n = n days.
The same here, if 1/5 work is done in 3 days total work is done in 5*3 = 15 days.
A's 1 day work is 1/20.
A's 2 days work is 2/20.
According to the question A work for 2 day's and on the third day.
B & C assists (**helps, not replaced).
So it goes like this.
A's first day + A's second day + (A + B + C) on third day, B & C helped.
i.e 2 1/20+1/20/+(1/20+1/30+1/60).
=>2/20+(1/20+1/30+1/60).
=>2/20+1/10.
= 1/5.
So for first 2 days and combining B and C on third day they will work 1/5th of a work.
All together (A+A+ (A+B+C) ) works for 3 days to get 1/5th of a work so.
If 1/n work is done in 1 days total work is done in 1*n = n days.
The same here, if 1/5 work is done in 3 days total work is done in 5*3 = 15 days.
(1)
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.
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.
Ashwini said:
1 decade ago
Can you explain how 6/60 came?
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