Aptitude - Time and Work - Discussion
Discussion Forum : Time and Work - General Questions (Q.No. 1)
1.
A can do a work in 15 days and B in 20 days. If they work on it together for 4 days, then the fraction of the work that is left is :
Answer: Option
Explanation:
| A's 1 day's work = | 1 | ; |
| 15 |
| B's 1 day's work = | 1 | ; |
| 20 |
| (A + B)'s 1 day's work = |  |
1 | + | 1 |  |
= | 7 | . |
| 15 | 20 | 60 |
| (A + B)'s 4 day's work = | |
7 | x 4 | |
= | 7 | . |
| 60 | 15 |
| Therefore, Remaining work = | |
1 - | 7 | |
= | 8 | . |
| 15 | 15 |
Discussion:
351 comments Page 20 of 36.
Mukesh gautam said:
1 decade ago
Simple method:
A-15.
B-20.
LCM is 60.
60/15 = 4.
60/20 = 3.
Total work 60 an total unit work done by a and b is 7.
In q4 day work are done than total 4 day work is 7x4 = 28.
Remaining work 60-28 = 32.
Fraction of remaining work is 32/60 = 8/15. Solution are done in only 20 sec. This method is very simple and less time consuming.
A-15.
B-20.
LCM is 60.
60/15 = 4.
60/20 = 3.
Total work 60 an total unit work done by a and b is 7.
In q4 day work are done than total 4 day work is 7x4 = 28.
Remaining work 60-28 = 32.
Fraction of remaining work is 32/60 = 8/15. Solution are done in only 20 sec. This method is very simple and less time consuming.
Arafat Neloy said:
1 decade ago
A can do a work in 15 days and B in 20 days.
A: 15 days-----1 work.
1 day-------1/15 work.
4 days------4/15 work.
B: 20 days-----1 work.
1 day-------1/20 work.
4 days------4/20 work or 1/5 work.
4/15 + 1/5 = 7/15.
Total work 1.
So, remaining work (1-7/15).
= 8/15 answer.
A: 15 days-----1 work.
1 day-------1/15 work.
4 days------4/15 work.
B: 20 days-----1 work.
1 day-------1/20 work.
4 days------4/20 work or 1/5 work.
4/15 + 1/5 = 7/15.
Total work 1.
So, remaining work (1-7/15).
= 8/15 answer.
Niral said:
1 decade ago
@Sushmoy.
(1 - 7/15) = 8/15.
Denominator of 1 will be 15 so it will be (15-7/15) = 8/15 will be answer.
(1 - 7/15) = 8/15.
Denominator of 1 will be 15 so it will be (15-7/15) = 8/15 will be answer.
Dnyaneshwar said:
1 decade ago
1*15 = 15.
15-8 = 7.
So that denominator remains same 7/15.
15-8 = 7.
So that denominator remains same 7/15.
Sushmoy said:
1 decade ago
(1-8/15) = 7/15 how is it possible? Please explain me.
Naren said:
1 decade ago
Dear friends, I have the doubt that why we take the total work as 1 instead of taking 60.
We take LCM of 15 & 20 as 60. So we consider 60 units as the total work. So we should take 60? Help me please.
We take LCM of 15 & 20 as 60. So we consider 60 units as the total work. So we should take 60? Help me please.
Priya said:
1 decade ago
How 7 came please tell me again?
Nagasuriya said:
1 decade ago
Dear friends how to solve this calculate 7/60 x4 =7/15 please explain me?
Sunil jat kantia said:
1 decade ago
Please solve this problem.
Er.Ketan Patel said:
1 decade ago
Take LCM is 60 mean total work done is 60.
It mean "a" can do 4 unit/day, "b" can do 3 unit/day.
Total 3+4 = 7/60.
Both do work together 4 days mean (7*4=28).
They complete the work 28 (60-28=32).
32/60 = 8/15.
It mean "a" can do 4 unit/day, "b" can do 3 unit/day.
Total 3+4 = 7/60.
Both do work together 4 days mean (7*4=28).
They complete the work 28 (60-28=32).
32/60 = 8/15.
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