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:
68 comments Page 6 of 7.
Ved Prakash Singh said:
8 years ago
4/20+x/20+x/12=1.
X=6 so total days=6+4=10days.
X=6 so total days=6+4=10days.
Shree said:
8 years ago
Clear and detailed explanation. Thank you.
Prienka said:
7 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?
Tom Cruz said:
7 years ago
x/20 + (x-4)/12 = 1,
12x + 20x - 80 = 240,
32x = 320,
x = 10 days.
12x + 20x - 80 = 240,
32x = 320,
x = 10 days.
(2)
Inba said:
7 years ago
How come 4/5?
Please explain.
Please explain.
Lakshit said:
7 years ago
@Shweta.
Can you please elaborate last line?
Can you please elaborate last line?
Akil Prakash said:
7 years ago
Thank you @Inna Reddy Chilakala.
Gouri said:
7 years ago
X=>20 and Y=>12.
L.C.M. of 20&12=>60.
The efficiency of X is 3 and of Y is 5,
3 * 4 = 12 (here 3 is the efficiency of X and 4 is the no: of days he worked alone)
remaining work=60-12=48,
8*x=48 (here 3+5=8),
x=48/8; x=6.
According to the question we want to know how many days work went on
so, 4+6 =10 days.
L.C.M. of 20&12=>60.
The efficiency of X is 3 and of Y is 5,
3 * 4 = 12 (here 3 is the efficiency of X and 4 is the no: of days he worked alone)
remaining work=60-12=48,
8*x=48 (here 3+5=8),
x=48/8; x=6.
According to the question we want to know how many days work went on
so, 4+6 =10 days.
(2)
Ims said:
7 years ago
X=20,Y=12.
SO LCM=60
X=3 unit /day.
Y=5 unit /day.
According to the question;
x work for 4 days alone so 3 *4 = 12.
So 60-12=48.
X+y=8 units.
Therefore, 48÷8=6.
So, 6+4(days of A alone works) = 10.
SO LCM=60
X=3 unit /day.
Y=5 unit /day.
According to the question;
x work for 4 days alone so 3 *4 = 12.
So 60-12=48.
X+y=8 units.
Therefore, 48÷8=6.
So, 6+4(days of A alone works) = 10.
(4)
Sudharsan said:
6 years ago
Why we are adding +4 to the sum the 6 is the work completed until the last. X+4 is just a time taken, why anyone explain?
(3)
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