Aptitude - Time and Work - Discussion
Discussion Forum : Time and Work - General Questions (Q.No. 9)
9.
A does 80% of a work in 20 days. He then calls in B and they together finish the remaining work in 3 days. How long B alone would take to do the whole work?
23 days
37 days
37
40 days
Answer: Option
Explanation:
| Whole work is done by A in |  |
20 x | 5 |  |
= 25 days. |
| 4 |
| Now, | |
1 - | 4 | |
i.e., | 1 | work is done by A and B in 3 days. |
| 5 | 5 |
Whole work will be done by A and B in (3 x 5) = 15 days.
| A's 1 day's work = | 1 | , (A + B)'s 1 day's work = | 1 | . |
| 25 | 15 |
 B's 1 day's work = |
|
1 | - | 1 | |
= | 4 | = | 2 | . |
| 15 | 25 | 150 | 75 |
| So, B alone would do the work in | 75 | = 37 | 1 | days. |
| 2 | 2 |
Discussion:
164 comments Page 17 of 17.
Keerthu said:
11 months ago
A in 80% work done 20 days.
A in 100% work done 100*20/80= 25 days.
A+B in 20% work done 3 days.
A+B in 100% work done 100*3/20= 15 days.
A = 25 days.
A+B = 15 days.
LCM OF 75.
1 DAY OF WORK 75/25 = 3
1 DAY A+B WORK 75/15 = 5.
A + B = 5
3 + B = 5
B = 2
B total working days =>75/2 = 37.5 days.
A in 100% work done 100*20/80= 25 days.
A+B in 20% work done 3 days.
A+B in 100% work done 100*3/20= 15 days.
A = 25 days.
A+B = 15 days.
LCM OF 75.
1 DAY OF WORK 75/25 = 3
1 DAY A+B WORK 75/15 = 5.
A + B = 5
3 + B = 5
B = 2
B total working days =>75/2 = 37.5 days.
(50)
Taraka Siva Sai Ponnuru said:
10 months ago
Given
A completes 80% work in 20 days (20% work in 5 days).
A alone can complete 100% work in 25days(20/80*100=25)
A+B together complete 20% of the work in 3 days
A+B together complete 100% of the work in 15 days.
Here we need to consider only 100% work done by A+B&A.
(A+B)-A = [1/15 - 1/25].
LCM of 15, 25 is 75.
(A+B)-A = [5-3]/75,
(A+B)-A = 2/75,
(A+B)-A = 37.5.
A completes 80% work in 20 days (20% work in 5 days).
A alone can complete 100% work in 25days(20/80*100=25)
A+B together complete 20% of the work in 3 days
A+B together complete 100% of the work in 15 days.
Here we need to consider only 100% work done by A+B&A.
(A+B)-A = [1/15 - 1/25].
LCM of 15, 25 is 75.
(A+B)-A = [5-3]/75,
(A+B)-A = 2/75,
(A+B)-A = 37.5.
(16)
Aliya said:
9 months ago
A's work rate = 80% in 20.days =80%/20=4
Remaining work of A and B = 100%-80%= 20% in 3 days = 20%/3.
B can do work = 20/3 - 4 = 20-12/3 = 8/3%.
B 100% work = 100/8/3 = 37.5 days.
Remaining work of A and B = 100%-80%= 20% in 3 days = 20%/3.
B can do work = 20/3 - 4 = 20-12/3 = 8/3%.
B 100% work = 100/8/3 = 37.5 days.
(32)
Imtiyaz said:
8 months ago
A can do 80% of work in 20 days.
A + B 20% of work in 3 days.
A alone can do 20% of work in 5 days and A+B can do 80% in 12 days.
Now, A 100% in 25 days and A + B in 15 days.
L.C.M of 15 and 25 = 75
The efficiency of A is 3/day and of A + B 5/day.
If A efficiency is 3, then B is 2.
B days = work/B efficiency.
=> 75/2 = 37.5.
A + B 20% of work in 3 days.
A alone can do 20% of work in 5 days and A+B can do 80% in 12 days.
Now, A 100% in 25 days and A + B in 15 days.
L.C.M of 15 and 25 = 75
The efficiency of A is 3/day and of A + B 5/day.
If A efficiency is 3, then B is 2.
B days = work/B efficiency.
=> 75/2 = 37.5.
(8)
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