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:
344 comments Page 5 of 35.
Raghavan said:
7 years ago
The LCM of 15 and 20 is 60 which means total work done=60. Then the efficiency of a & b are 4 & 3 respectively(one-day efficiency). Now if both work together their efficiencies must be added which is =7 and therefore 7*4=24.
Is the work was done by them for 4 days which means the leftover is 60-24=36.
Am I right?
Is the work was done by them for 4 days which means the leftover is 60-24=36.
Am I right?
Basivireddy said:
9 years ago
Hi guys, this is Basivireddy.
A can be work in 15 days = 1/15.
B Can be work in 30 days = 1/30.
1/15 + 1/30.
7/60 this is one day work.
We want 4 days work that's why it is 4*7/60 = 28/60 = 7/15.
Now one day work means they left one day so.
1-7/15 = 8/15, I hope so you understood, Thank you guys, have a great day.
A can be work in 15 days = 1/15.
B Can be work in 30 days = 1/30.
1/15 + 1/30.
7/60 this is one day work.
We want 4 days work that's why it is 4*7/60 = 28/60 = 7/15.
Now one day work means they left one day so.
1-7/15 = 8/15, I hope so you understood, Thank you guys, have a great day.
TRUPTIMAYEE BAHINIPATI said:
7 years ago
Why we subtract 7/15 by 1?
Solution:
Here we consider that the total work is 1.
A&B do a certain work that we don't know so at first we need find the unit of work in 1day
then A+B's working unit per 4 days.
After that we got A&B's total unit of work done ;which is substrated by 1 to got the remaining work.
Solution:
Here we consider that the total work is 1.
A&B do a certain work that we don't know so at first we need find the unit of work in 1day
then A+B's working unit per 4 days.
After that we got A&B's total unit of work done ;which is substrated by 1 to got the remaining work.
Avinash Ghadge said:
1 decade ago
@Deppa.
1/15 & 1/20 hear denominator are not same ok. So firstly we have to make both same. So 1/15 are multiply bye 4 on both numerator, denominator we get:
1*4/15*4 = 4/60.
1*3/20*3 = 3/60 this value are getting now adding this two value, we get.
4+3/60 = 7/60.
That's it. I hope you understand.
1/15 & 1/20 hear denominator are not same ok. So firstly we have to make both same. So 1/15 are multiply bye 4 on both numerator, denominator we get:
1*4/15*4 = 4/60.
1*3/20*3 = 3/60 this value are getting now adding this two value, we get.
4+3/60 = 7/60.
That's it. I hope you understand.
Mangu said:
1 decade ago
Let's total total work is 1.
A can do in 15 days.
A can do it in 1 days = 1/15.
Similarly B can do it = 1/20.
They work totally in a day = 1/15+1/20 = 7/60.
A and B do together in 4 days.
So work done in 4 days = 7/60x4 = 7/15.
Then left work is, Total work - 4 days work. i.e, 1-7/15 = 8/7 (Ans).
A can do in 15 days.
A can do it in 1 days = 1/15.
Similarly B can do it = 1/20.
They work totally in a day = 1/15+1/20 = 7/60.
A and B do together in 4 days.
So work done in 4 days = 7/60x4 = 7/15.
Then left work is, Total work - 4 days work. i.e, 1-7/15 = 8/7 (Ans).
Ankita said:
4 years ago
@Jyoti.
It's 1 -7/15 as it is asking how much work is left. Which means 1 is the total amount of work, and 7/15 is the amount of work completed.
So, to get the remaining work we hv to subtract the work done by the whole work. Which is
1-7/15.
= 15/15 - 7/15.
= 15-7/15.
= 8/15.
Hope it helps.
It's 1 -7/15 as it is asking how much work is left. Which means 1 is the total amount of work, and 7/15 is the amount of work completed.
So, to get the remaining work we hv to subtract the work done by the whole work. Which is
1-7/15.
= 15/15 - 7/15.
= 15-7/15.
= 8/15.
Hope it helps.
(15)
RANGADHAR said:
10 years ago
If the total work is taking the LCM of 15 & 20.
Then it will be 60.
A = 15 days.
B = 20 days.
LCM = 60 work.
Then A do in one day = 60/15 = 4 work.
B = 60/20 = 3 work.
In one day they work = {4+3} work.
In 4 days = 7*4 = 28 works.
Remaining = 60-28 = 32 work.
Then 32/60 = 8/15.
Then it will be 60.
A = 15 days.
B = 20 days.
LCM = 60 work.
Then A do in one day = 60/15 = 4 work.
B = 60/20 = 3 work.
In one day they work = {4+3} work.
In 4 days = 7*4 = 28 works.
Remaining = 60-28 = 32 work.
Then 32/60 = 8/15.
Anshu said:
1 decade ago
"A" can can do a work in 15 days therefore he did 1/15 of the work in a day.
"B" can do the same work in 20 days therefore he did 1/20 of the work in a day.
Therefore.
[1/15 + 1/20]4 = [4/60 + 3/60]4.
[7/60]4 = 7/15 of the work done.
The total work left = 1 - 7/15 = 15 - 7/ 15 = 8/15.
"B" can do the same work in 20 days therefore he did 1/20 of the work in a day.
Therefore.
[1/15 + 1/20]4 = [4/60 + 3/60]4.
[7/60]4 = 7/15 of the work done.
The total work left = 1 - 7/15 = 15 - 7/ 15 = 8/15.
Ashwini G C said:
9 years ago
Hi friends,
Happy to see you all discussing the problems and the solution given by each of them is awesome.
In fact, I could solve the problem by seeing this 'discussion forum'. I had all the doubts as others had and I used to get a solution for it. So, I thought of thanking you all.
Happy to see you all discussing the problems and the solution given by each of them is awesome.
In fact, I could solve the problem by seeing this 'discussion forum'. I had all the doubts as others had and I used to get a solution for it. So, I thought of thanking you all.
Shashi kant said:
10 years ago
A's days = 15.
B's days = 20.
LCM of both = 60 (total work also).
A's work per day = 60/15 = 4.
B's work per day = 60/20 = 3.
Both can do work in one day = (4+3) = 7.
4 days work of both = 7*4 = 28.
Then remaining work = (60-28) = 32.
So please tell me how can I fractionate it?
B's days = 20.
LCM of both = 60 (total work also).
A's work per day = 60/15 = 4.
B's work per day = 60/20 = 3.
Both can do work in one day = (4+3) = 7.
4 days work of both = 7*4 = 28.
Then remaining work = (60-28) = 32.
So please tell me how can I fractionate it?
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