Aptitude - Time and Work - Discussion
Discussion Forum : Time and Work - General Questions (Q.No. 13)
13.
A and B can together finish a work 30 days. They worked together for 20 days and then B left. After another 20 days, A finished the remaining work. In how many days A alone can finish the work?
Answer: Option
Explanation:
| (A + B)'s 20 day's work = |  |
1 | x 20 |  |
= | 2 | . |
| 30 | 3 |
| Remaining work = | |
1 - | 2 | |
= | 1 | . |
| 3 | 3 |
| Now, | 1 | work is done by A in 20 days. |
| 3 |
Therefore, the whole work will be done by A in (20 x 3) = 60 days.
Discussion:
63 comments Page 5 of 7.
Sarvesh said:
1 decade ago
A and B together complete the work in 30 days.
So (A+B) 1 day work is (1/30).
B worked for 20 days & left, so A did the remaining 10 days effective work alone in another 20 days.
10 days remaining work ---> A took 20 days.
Therefore 30 days work(i.e 1 complete work) is done in----> (20/10)*30 = 60 days.
So (A+B) 1 day work is (1/30).
B worked for 20 days & left, so A did the remaining 10 days effective work alone in another 20 days.
10 days remaining work ---> A took 20 days.
Therefore 30 days work(i.e 1 complete work) is done in----> (20/10)*30 = 60 days.
Ars said:
1 decade ago
In question it self given that A did the remaining work in 20 days.
Kaaly said:
1 decade ago
" very simple explanation "
Total work = (A+B) = 1/30.
B left the work = 1/20.
B -(A+B) = 1/20-1/30 = 1/60.
Total work = (A+B) = 1/30.
B left the work = 1/20.
B -(A+B) = 1/20-1/30 = 1/60.
Godse said:
1 decade ago
a+b = 1/30.
a+b = x/20.
a = y/20.
So,
1/30 = x/20.
x = 20/30.
= 2/3.
Given,
x+y = 1.
y = 1-(2/3).
= 1/3.
Given,
a = y/20.
= 1/60.
So 60 days.
a+b = x/20.
a = y/20.
So,
1/30 = x/20.
x = 20/30.
= 2/3.
Given,
x+y = 1.
y = 1-(2/3).
= 1/3.
Given,
a = y/20.
= 1/60.
So 60 days.
Praveen said:
1 decade ago
Consider 100% of the work can be completed by both A & B in 30 days, so this implies.
In 1 day A & B can complete 3.33% of work.
So A & B worked for 20 days which means they both completed 3.33*20 = 66.66% of work.
And now A alone need to finish 33.33% of work. But A finished in 20 days, which means.
A's Productivity is 1.66% per 1 day.
So A alone can complete it in = 60 days.
In 1 day A & B can complete 3.33% of work.
So A & B worked for 20 days which means they both completed 3.33*20 = 66.66% of work.
And now A alone need to finish 33.33% of work. But A finished in 20 days, which means.
A's Productivity is 1.66% per 1 day.
So A alone can complete it in = 60 days.
Raj said:
1 decade ago
In how many days B alone can finish the work?
VANI said:
1 decade ago
@Ankush.
Here in question said that 1/3 work is done by A after another 20 days. So we done 20*3.
Here in question said that 1/3 work is done by A after another 20 days. So we done 20*3.
Deepak yadav said:
1 decade ago
Please give its short trick.
Pooja bhardwaj said:
8 years ago
Thank you for the best and easy explanation @Kaaly and @Senchu Thomas.
Balaji rajendran said:
10 years ago
@Raj.
B alone can finish the work in 60 days same as A.
A+B = 1/30 and A = 1/60 then B = 1/30-1/60 = 1/60. So B alone can finish the work in 60 days.
B alone can finish the work in 60 days same as A.
A+B = 1/30 and A = 1/60 then B = 1/30-1/60 = 1/60. So B alone can finish the work in 60 days.
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