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 16 of 36.
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.
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)
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.
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.
Sunil said:
1 decade ago
@Nikita answer is fantastic.
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.
Raj said:
1 decade ago
Question is on every 3rd day, it means from 20 days B and C will assist him on every 3rd day. So count every 3rd day till 20 days.
So we get 6 days. It means B and C will assist him 6 days from 20 days i.e. on 3rd, 6th, 9th, 12th, 15th and 18th day. I think the answer is 16.
So we get 6 days. It means B and C will assist him 6 days from 20 days i.e. on 3rd, 6th, 9th, 12th, 15th and 18th day. I think the answer is 16.
Suribabu said:
1 decade ago
In this problem first we understand the work done till 3rd days.
A can do his work for 2 days (2*(1/20)) and the 3rd day. A can do work with B & C i.e. 1/20+1/30+1/60 = 1/10 so up-to 3 days.
A can do 1/10+1/10 = 1/5 work (3 days work) then total work done in 3*5 = 15 days.
Hope understand.
A can do his work for 2 days (2*(1/20)) and the 3rd day. A can do work with B & C i.e. 1/20+1/30+1/60 = 1/10 so up-to 3 days.
A can do 1/10+1/10 = 1/5 work (3 days work) then total work done in 3*5 = 15 days.
Hope understand.
Daniyar said:
1 decade ago
For 1st 2 days A will do work himself.
A's work in 1st 2 days:
(1/20)*2 = 1/10 or 0.1.
0.1 is 10% of total work done which is 1 or 100%.
On 3rd day B and C will assist A to do work.
A's, B's, and C's work in 3rd day:
(1/20+1/30+1/60)*1 = 1/10 or 0.1.
Again in this day three of them could do only another 10% of work out of 100% or 0.1 out of 1.
For 1st three days A, B, and C accomplished:
1/10+1/10 = 2/10, 0.2 or 20 % of total work out of 100% or 1.
To finish they need to accomplish 100-20 = 80 % or 0.8 of work remaining.
Having 20% or 3 days we need 15 (in which every 3rd day is assisted by B and C) more days (100%/20% = 5 => 5*3 = 15) to achieve total work accomplishment.
A's work in 1st 2 days:
(1/20)*2 = 1/10 or 0.1.
0.1 is 10% of total work done which is 1 or 100%.
On 3rd day B and C will assist A to do work.
A's, B's, and C's work in 3rd day:
(1/20+1/30+1/60)*1 = 1/10 or 0.1.
Again in this day three of them could do only another 10% of work out of 100% or 0.1 out of 1.
For 1st three days A, B, and C accomplished:
1/10+1/10 = 2/10, 0.2 or 20 % of total work out of 100% or 1.
To finish they need to accomplish 100-20 = 80 % or 0.8 of work remaining.
Having 20% or 3 days we need 15 (in which every 3rd day is assisted by B and C) more days (100%/20% = 5 => 5*3 = 15) to achieve total work accomplishment.
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