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:
359 comments Page 17 of 36.
Ganesh said:
10 years ago
Total work = 60 units (lcm of 20, 30 and 60).
A completes work in 20 days. It means 3 units a day.
B completes work In 30 days. It means 2 units a day.
C completes work in 60 days. It means 1 unit a day.
A is working 2 days alone. It means 3+3 = 6 units is completed.
On third day B and C helping A.
It means on third day 3 +2+1 = 6 units of work is completed.
It means for 3 days 12 units of work is completed.
For 60 units?
60*3/12 = 15.
A completes work in 20 days. It means 3 units a day.
B completes work In 30 days. It means 2 units a day.
C completes work in 60 days. It means 1 unit a day.
A is working 2 days alone. It means 3+3 = 6 units is completed.
On third day B and C helping A.
It means on third day 3 +2+1 = 6 units of work is completed.
It means for 3 days 12 units of work is completed.
For 60 units?
60*3/12 = 15.
Jitesh said:
10 years ago
A = 20.
B = 30.
C = 60.
LCM is 60 so a do the work in 1 day is 3 unit B is doing work in 1 day is 2 unit and C is 1 unit.
1st (A) day = 3.
2nd (A) day = 3.
3rd (A+B+C) day = 3+2+1 = 6.
Total work done in 3 days is 12 unit. So for 60 unit (60/12 = 5).
5*3 days = 15 days.
B = 30.
C = 60.
LCM is 60 so a do the work in 1 day is 3 unit B is doing work in 1 day is 2 unit and C is 1 unit.
1st (A) day = 3.
2nd (A) day = 3.
3rd (A+B+C) day = 3+2+1 = 6.
Total work done in 3 days is 12 unit. So for 60 unit (60/12 = 5).
5*3 days = 15 days.
Teja said:
1 decade ago
This is question which is completely related to alternate days.
In alternate days question whenever work done is not given you have to take it as '1'.
Here we got that 1/5 of the work is done in 3 days which means 1/5 work=3 days.
1=how many days?
Cross multiply, you get days=15.
This concept works for all of the alternate days question. When ever work is not given take it as '1'.
In alternate days question whenever work done is not given you have to take it as '1'.
Here we got that 1/5 of the work is done in 3 days which means 1/5 work=3 days.
1=how many days?
Cross multiply, you get days=15.
This concept works for all of the alternate days question. When ever work is not given take it as '1'.
Vani said:
1 decade ago
In last step why did they multiplied with 3?
Vicky said:
1 decade ago
Please anyone give clear explanation I confused.
Harry matharoo said:
1 decade ago
Now, 1/5 work is done in 3 days.
Whole work will be done in (3 x 5) = 15 days.
Where from 15 come from why we multiplied 3 with 5.
Whole work will be done in (3 x 5) = 15 days.
Where from 15 come from why we multiplied 3 with 5.
Venkat said:
1 decade ago
Please tell me how 3 is coming in the last step?
Venkat said:
1 decade ago
3 = 1/5.
So, our complete work done at 1.
So, 3*5 = 1/5*5.
15 = 1.
So, our complete work done at 1.
So, 3*5 = 1/5*5.
15 = 1.
Junaid said:
1 decade ago
A do 1/20 = 0.05 work daily and in 4 days he do 0.05+0.05+0.05+0.05 = 0.2 work.
But with the help of B and C the 4 days work is done in 3 days in this way.
= 0.05+0.05+(0.05+1/30+1/60) = 0.2.
Then every 4 days work is done in 3 days up-to 20 days.
So 3+3+3+3+3 = 15.
But with the help of B and C the 4 days work is done in 3 days in this way.
= 0.05+0.05+(0.05+1/30+1/60) = 0.2.
Then every 4 days work is done in 3 days up-to 20 days.
So 3+3+3+3+3 = 15.
Onkar said:
1 decade ago
A can complete a work in 20 days, B can complete the same work in 30 days and with the help of C together if they complete the work in 60 days, so assume total work to be done is 60. (LCM of 20, 30, 60).
Persons A B C per 3 day.
Days- 20 30 60 12 = 6+6.
Work/day- 3 2 1 5.
----------------------------------------------------------------.
Work - 60 60 60 60.
Per 3 day ----> 12.
How many ----> 60 = (60*3)/12 = 15 days required.
Days required.
Persons A B C per 3 day.
Days- 20 30 60 12 = 6+6.
Work/day- 3 2 1 5.
----------------------------------------------------------------.
Work - 60 60 60 60.
Per 3 day ----> 12.
How many ----> 60 = (60*3)/12 = 15 days required.
Days required.
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