Aptitude - Time and Work - Discussion
Discussion Forum : Time and Work - General Questions (Q.No. 16)
16.
X and Y can do a piece of work in 20 days and 12 days respectively. X started the work alone and then after 4 days Y joined him till the completion of the work. How long did the work last?
Answer: Option
Explanation:
| Work done by X in 4 days = |  |
1 | x 4 |  |
= | 1 | . |
| 20 | 5 |
| Remaining work = | |
1 - | 1 | |
= | 4 | . |
| 5 | 5 |
| (X + Y)'s 1 day's work = | |
1 | + | 1 | |
= | 8 | = | 2 | . |
| 20 | 12 | 60 | 15 |
| Now, | 2 | work is done by X and Y in 1 day. |
| 15 |
| So, | 4 | work will be done by X and Y in | |
15 | x | 4 | |
= 6 days. |
| 5 | 2 | 5 |
Hence, total time taken = (6 + 4) days = 10 days.
Discussion:
69 comments Page 4 of 7.
Akhil said:
1 decade ago
Can anyone explain this problem clearly.
Prienka said:
8 years ago
Why we are calculating total time taken i.e 6+4 days. The question was asked how long did the work last?
Should it be 6 days only right? Anybody can clear my confusion?
Should it be 6 days only right? Anybody can clear my confusion?
Inba said:
8 years ago
How come 4/5?
Please explain.
Please explain.
Lakshit said:
8 years ago
@Shweta.
Can you please elaborate last line?
Can you please elaborate last line?
Akil Prakash said:
8 years ago
Thank you @Inna Reddy Chilakala.
Riya said:
2 weeks ago
X can work per day = 1/20.
Y can work per day = 1/12.
X worked alone for 4 days: 1/20 * 4 = 1/5.
The remaining work :1 - 1/5 = 4/5.
The remaining work is completed together: X + Y per day = 1/20 + 1/12 = 2/15 per day.
Time=remaining work/the remaining work done per day = 4/5 divided by 2/15 = 6 days.
The total work = A's done work alone + together work = 4 + 6 = 10 days.
Y can work per day = 1/12.
X worked alone for 4 days: 1/20 * 4 = 1/5.
The remaining work :1 - 1/5 = 4/5.
The remaining work is completed together: X + Y per day = 1/20 + 1/12 = 2/15 per day.
Time=remaining work/the remaining work done per day = 4/5 divided by 2/15 = 6 days.
The total work = A's done work alone + together work = 4 + 6 = 10 days.
Jjjjjjjjjj said:
2 decades ago
Please explain clealrly.
Santosh said:
2 decades ago
Well a simple logic
1day work x =1/20
y=1/12
x first start and works upto 4 days=4*1/20
then both x and y works upto some day to completework=a(1/20+1/12)
add (4*1/20)+a(1/20+1/12)=1
we will get the days where both x and y worked=a=6
So total days to complete work =4+6=10.
1day work x =1/20
y=1/12
x first start and works upto 4 days=4*1/20
then both x and y works upto some day to completework=a(1/20+1/12)
add (4*1/20)+a(1/20+1/12)=1
we will get the days where both x and y worked=a=6
So total days to complete work =4+6=10.
Sree said:
2 decades ago
How 6+4?y should we add. Please help.
Sahib said:
2 decades ago
Take it this way
1/5 work x does in 4 days
Remaining 4/5 is to be found
X+y does 1/20+1/12 in 1 day
Therefore x+y=2/15 w/d
Therefore 4/5 w = 2/15(w/d)/4/5(w)
We get 1/6(1/d)
Therefore 6 days
Therefore total wrk in 10 days
1/5 work x does in 4 days
Remaining 4/5 is to be found
X+y does 1/20+1/12 in 1 day
Therefore x+y=2/15 w/d
Therefore 4/5 w = 2/15(w/d)/4/5(w)
We get 1/6(1/d)
Therefore 6 days
Therefore total wrk in 10 days
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