Aptitude - Time and Work - Discussion

2(1/8+1/10+1/12)+x(1/10+1/12)=1 we get x value is 2.09. required value is 11am+209=1.09pm,we taken approx value 1pm.

Hi Friends,

1) P worked from 9 AM to 11 AM (2 hours of work time).

2) In two hours it can print 25,000 books ( Since, 100,000 books in 8 hours it can Print)

3) So remaining 75000 books has to be printed by other two machines (Q and R).

4) Compute the capacity of Q and R, viz : Q+R = ((1/10)+(1/12))= 11/60 = 5.45 hours.

5) So lets put ourself a question. Both the machine needs 5.45 hours to Print 100,000 books. But already 25,000 books has been printed by Machine P. To print remaining 75,000 books Q and R will be needing approximately 4 hours.

Viz; Let x be the number of hours required by Q and R to print 75,000 books.

x = [(5.45*75,000)/100,000] = 4 hours (approximately).

6) All the machines started at 9 Am. Hence 9 + 4 = 13 (1.00 pm).

Can anyone tell

Why you put last step as 9am+4?

Already p, q, r done by 2hrs and (q&r) in 4 hrs know.

Then 2+4=6 only know.

On this step I am in confusion. Help me.

Friends

P's 2 hr work = 1/8*2=1/4
rest 3/4 work done by q&r
q+r 1hr = 1/10 + 1/12=11/60 work
3/4 work by q&r=60/11 * 3/4=4.09

The work complete time was 9a.m+4=1p.m

Thanks naveen sir.

Since machine p stops after 37 units of work is completed from 60 units of work, still (60-37=23) 23units of work is remaining. hence, 1-(37/60)= 23/60

Can some one tell me why 1-37/60 ?

Hi friends... In this problem it is having some confusion in the last step....i will explain that step in a easy way....

The work completed by q and r after closing of p machine is
23/60....
but we don't know the time...
we have to calculate it...

(q+r)'s 1 hour work = 11/60.

we can represent the above relation like this....

11/60 (portion of work)-------> 1 hour (time)

23/60 (portion of work) ------> ....? (time)


By cross multiplying the above terms we will get.

11/60 * 60/23 = 23/11

that is approximately equals to 2 ....

q and r machines took 2 hours to complete the remaining work....

i.e.,
11+2 = 1 p.m

the total 1 lakh books will be printed by 1 p.m

Hey is above told methods are applicable? to this type of problems with a small change.

Easy Solution

let total time to print the book be x
therefore
x-2/8 + x/10 + x/12= 1
Solve for x we get approx 4
so time will be 9+4=1 pm.