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 10 of 17.
Satish said:
9 years ago
A - 20 - 80/100.
A - 1 - 80/(100 * 20) = 1/25.
A and B - 3 days = 20/100.
" 1 " = 20/(100 * 3).
= 1/15.
So,
1/15 -1/25 = 75/2.
A - 1 - 80/(100 * 20) = 1/25.
A and B - 3 days = 20/100.
" 1 " = 20/(100 * 3).
= 1/15.
So,
1/15 -1/25 = 75/2.
SHIMEGHA.T.C said:
8 years ago
3(A+B)20%. = 80%(20A),
3/20*100. = 20/80*100A
15days(a+b). = 25 days A alone
B alone work = 1/25-1/15 = 2/75; 75/2.
3/20*100. = 20/80*100A
15days(a+b). = 25 days A alone
B alone work = 1/25-1/15 = 2/75; 75/2.
Ram@Sravs said:
1 decade ago
Hi. @Supreeth:
In St-4:
Why had you reversed the 2/25 part to 25/2 and multiplied with 3?
Can you Explain please.
In St-4:
Why had you reversed the 2/25 part to 25/2 and multiplied with 3?
Can you Explain please.
Juanita said:
1 decade ago
My understanding is that A alone does 80% work which is 5/4. Remaining 20% work is done by A & B which is 1/5.
Abhik said:
7 years ago
A 80% done in 20 days 100% done in 25 days.
Another A+B done 20%in 3 days 100% in 15 days.
Now B = 25*15/10=37.5.
Another A+B done 20%in 3 days 100% in 15 days.
Now B = 25*15/10=37.5.
Snehagoud said:
1 decade ago
A did only 80% of work out of total work in 20 days so
work done by A=80/100=5/4
so total workdone by A=20*5/4
work done by A=80/100=5/4
so total workdone by A=20*5/4
Srujan said:
1 decade ago
Am getting troubled like this questions, can any one knows the tricks to solve these kind of problems.
Saiteja said:
8 years ago
20 days-80% => 1 day-4%.
In 3 days a+b-20% => 3b=20-3*4% = 8%.
b = 8/3% => 100*8/3 = 37.5.
In 3 days a+b-20% => 3b=20-3*4% = 8%.
b = 8/3% => 100*8/3 = 37.5.
Vijay said:
6 years ago
1day work of A : (1/20)*80/100 = 1/25,
A+B = 3/25 + 3/x=1/5(for 3days).
Find x = 37.5.
A+B = 3/25 + 3/x=1/5(for 3days).
Find x = 37.5.
Balaji said:
1 decade ago
I can't understand the simple step anyone friends tell me (1/15-1/25) please tell me?
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