Discussion :: Time and Work
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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 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 ![]() |
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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