66.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
(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.
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