Question: 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 ?
[A].
11:30 A.M. |
[B].
12 noon |
[C].
12:30 P.M. |
[D].
1:00 P.M. |
Answer: Option D
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.
