Aptitude - Time and Work - Discussion
Discussion Forum : Time and Work - General Questions (Q.No. 14)
14.
P can complete a work in 12 days working 8 hours a day. Q can complete the same work in 8 days working 10 hours a day. If both P and Q work together, working 8 hours a day, in how many days can they complete the work?
Answer: Option
Explanation:
P can complete the work in (12 x 8) hrs. = 96 hrs.
Q can complete the work in (8 x 10) hrs. = 80 hrs.
 P's1 hour's work = |
1 | and Q's 1 hour's work = | 1 | . |
| 96 | 80 |
| (P + Q)'s 1 hour's work = |  |
1 | + | 1 |  |
= | 11 | . |
| 96 | 80 | 480 |
| So, both P and Q will finish the work in | |
480 | |
hrs. |
| 11 |
| Number of days of 8 hours each = |
|
480 | x | 1 | |
= | 60 | days = 5 | 5 | days. |
| 11 | 8 | 11 | 11 |
Discussion:
57 comments Page 5 of 6.
Srikanth said:
1 decade ago
Why should we take 11/480 as 480/11 ?
Akila said:
1 decade ago
11/480 is the part of work completed in 1 hour.
If we reverse it we can get time.
If we reverse it we can get time.
Sagarika said:
1 decade ago
We can do this by taking up the lcm of both's working hours to complete the task i.e., of 96 and 80 which comes to be 480.
So if the whole work is considered to be 480parts then P can complete in 480/96=5 days and Q can in 480/80=6 days and if they work together then 480/(5+6) days.
If they work 8 hours each then
=(480/11*1/8) days
= 480/88
= 5.454545.. or 5(5/11)
So if the whole work is considered to be 480parts then P can complete in 480/96=5 days and Q can in 480/80=6 days and if they work together then 480/(5+6) days.
If they work 8 hours each then
=(480/11*1/8) days
= 480/88
= 5.454545.. or 5(5/11)
Hanmant said:
2 decades ago
How come 11/480?
Shekha said:
1 decade ago
Sagarika your explanation is very simple. And Rani maria thanks for thinking me simple.
Sikha said:
1 decade ago
Why multipled by 1/8 not 8?
Anshik said:
1 decade ago
Why multiplied by 1/8 and not 8 ?
Nagarjun said:
1 decade ago
@sikha,anshik
for 1 day they work 8hrs
for x days they work 480/11 hrs
so x=(480/11)*(1/8)
thats it....
for 1 day they work 8hrs
for x days they work 480/11 hrs
so x=(480/11)*(1/8)
thats it....
Sourya said:
1 decade ago
They worked 8 hours for 1 day
" " 1 " " 1/8 day
So, 480/11 " " (480/11)*1/8 day= 60/11 days= 5 5/11
" " 1 " " 1/8 day
So, 480/11 " " (480/11)*1/8 day= 60/11 days= 5 5/11
Deeps said:
1 decade ago
Why should we take the reverse of 480/11 and multiply?
Why shouldnt we directly multiply?
Why shouldnt we directly multiply?
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