"Two things are infinite: the universe and human stupidity; and I'm not sure about the universe."
- Albert Einstein
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?
[A].
5
5
11
[B].
5
6
11
[C].
6
5
11
[D].
6
6
11
Answer: Option A
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.
11/480 is the addition of 1/96+1/80
(1*5)/(96*5)+(1*6)/(80*6)=5/480+6/480=11/480
Asha said:
(Thu, Jul 8, 2010 10:03:26 AM)
When we divide 60 by 11 the quotient is 5 and the remainder is 5 11 is the divisor? so 5 5/11.
Nagu said:
(Mon, Jul 12, 2010 03:10:38 AM)
Hi all
we can write 60/11 = (5*11+5)/11
= (55+11)/11
it is same as 5 5/11 here first first 5 is quocient and senocd 5 is remainder and 11 is deviser
Neha said:
(Sun, Aug 1, 2010 02:45:49 AM)
Why multiplied by (1/8)?
Rani Maria said:
(Tue, Aug 3, 2010 10:51:24 PM)
Take the LCM of 96,80 then we get 480.
then 1/96 * 480 + 1/80 *480 = 5/480 + 6/480 = 11/480.
Chintan said:
(Sat, Aug 7, 2010 08:39:15 AM)
Neha. . They work to gather 8 hours in 1 day that is shown in que. So ans mult. By 1/8
Supriya said:
(Sun, Aug 22, 2010 04:57:40 AM)
How can we solve this 480/11 * 1/8..and how came the ans 60/11 ?
Srinivasareddy said:
(Tue, Aug 31, 2010 10:12:14 AM)
P can do the work in 12days. He do per day 8 hours.
P can do work in total hours is:96.
Same as Q can do work in:80hours.
P's one day work is:1/96.
Q's one day work is:1/80.
P+q one day work is:1/96+1/80=11/480.
P+q work is:480/11.
P+q can done 8 hours per day:480/11*1/8.
Srikanth said:
(Tue, Sep 7, 2010 02:29:12 PM)
Why should we take 11/480 as 480/11 ?
Akila said:
(Fri, Sep 17, 2010 02:02:23 AM)
11/480 is the part of work completed in 1 hour.
If we reverse it we can get time.
Sagarika said:
(Sun, Oct 3, 2010 07:44:01 AM)
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)
Shridhar said:
(Fri, Nov 26, 2010 06:10:14 AM)
Sagarika your explaination is very nice.
Shekha said:
(Fri, Dec 10, 2010 10:51:06 PM)
Sagarika your explanation is very simple. And Rani maria thanks for thinking me simple.
Sikha said:
(Sat, Dec 18, 2010 09:17:34 PM)
Why multipled by 1/8 not 8?
Anshik said:
(Wed, Jan 12, 2011 01:40:07 AM)
Why multiplied by 1/8 and not 8 ?
Nagarjun said:
(Fri, Jan 14, 2011 09:14:52 AM)
@sikha,anshik
for 1 day they work 8hrs
for x days they work 480/11 hrs
so x=(480/11)*(1/8)
thats it....
Sourya said:
(Mon, Jul 18, 2011 05:25:28 AM)
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
Deeps said:
(Wed, Aug 17, 2011 06:57:18 AM)
Why should we take the reverse of 480/11 and multiply?
Why shouldnt we directly multiply?
Sush said:
(Fri, Aug 26, 2011 10:06:06 PM)
@Deeps
For 1hr-11/480th part of work is done.
So, to complete whole work it'll take 480/11hrs.
Eg:
For 1hr-1/4th f work
For xhr-1(whole) work..? x=4hrs.
Just take it to the l.h.s from r.h.s thats it.
Hope you are clear now...:)
Asha said:
(Fri, Sep 16, 2011 06:39:11 PM)
Ok now look at the theorem. as per the theorem if A does a work in x days and B does the same work in y days then total no of days taken by A&B to complete the same work is xy/x+y
Now for the question the equation would be (12*8)*(8*10)/ 12*8+10*8= 480/11
The answer obtained is in hrs, to convert this in no of days divide it by 8 as A/B does the work 8hrs in a day, now the answer becomes 60/11 which is the required answer..
P's1 hour's work =
