Aptitude - Time and Work - Discussion
Discussion Forum : Time and Work - General Questions (Q.No. 10)
10.
A machine P can print one lakh books in 8 hours, machine Q can print the same number of books in 10 hours while machine R can print them in 12 hours. All the machines are started at 9 A.M. while machine P is closed at 11 A.M. and the remaining two machines complete work. Approximately at what time will the work (to print one lakh books) be finished ?
Answer: Option
Explanation:
| (P + Q + R)'s 1 hour's work = |  |
1 | + | 1 | + | 1 |  |
= | 37 | . |
| 8 | 10 | 12 | 120 |
| Work done by P, Q and R in 2 hours = | |
37 | x 2 | |
= | 37 | . |
| 120 | 60 |
| Remaining work = | |
1 - | 37 | |
= | 23 | . |
| 60 | 60 |
| (Q + R)'s 1 hour's work = | |
1 | + | 1 | |
= | 11 | . |
| 10 | 12 | 60 |
| Now, | 11 | work is done by Q and R in 1 hour. |
| 60 |
| So, | 23 | work will be done by Q and R in | |
60 | x | 23 | |
= | 23 | hours  2 hours. |
| 60 | 11 | 60 | 11 |
So, the work will be finished approximately 2 hours after 11 A.M., i.e., around 1 P.M.
Discussion:
95 comments Page 7 of 10.
Priyadharshini said:
3 years ago
P = 2/8, Q = (2+x)/10, R = (2+x)/12.
(2/8)+(2+x)/10+(2+x)/12 = 1.
By solving this equation we get x = 2 hrs.
so the answer is 1PM (11AM+2hrs).
(2/8)+(2+x)/10+(2+x)/12 = 1.
By solving this equation we get x = 2 hrs.
so the answer is 1PM (11AM+2hrs).
(15)
Shashank said:
1 decade ago
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.
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.
Swapna Vallala said:
8 years ago
The difference between every machine is two hours, so 2hr + 11hr = 13 hrs, ie 1:00 clock. This is an easy method for understanding.
Shekar said:
1 decade ago
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.
Shobith said:
1 decade ago
That total of "1" represents the one day.
In the step 2*1/8+(1/80)*x+(1/12)x = 1.
Right @Sameer.
In the step 2*1/8+(1/80)*x+(1/12)x = 1.
Right @Sameer.
Swapnil said:
8 years ago
Can someone tell me why 1 is subtracted in third step after getting two hours work.
1-37/60 ? Why?
1-37/60 ? Why?
Sukanya said:
9 years ago
The difference between every machine is two hours, so 2hr + 11hr = 13 hrs, ie 1:00 clock.
(2)
Gayu said:
1 decade ago
Hey is above told methods are applicable? to this type of problems with a small change.
Devi said:
8 years ago
How to calculate 2 hours from 23/11 hours? Please help me, I'm in confusion.
Vikash said:
1 decade ago
What about the 0.09 hr left in the answer which doesn't add to the answer?
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