Question
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 the same in 12 hours. All the machines started printing at 9 A.M. Machine P is stopped at 11 A.M. and the remaining two machines complete work. Approximately at what time will the printing of one lakh books be completed?
Answer: Option C
WORK DONE BY P IN 1 HOUR = 1/8
WORK DONE BY Q IN 1 HOUR = 1/10
WORK DONE BY R IN 1 HOUR = 1/12
WORK DONE BY P,Q AND R IN 1 HOUR = 1/8 + 1/10 + 1/12 = 37/120
WORK DONE BY Q AND R IN 1 HOUR = 1/10 + 1/12 = 22/120 = 11/60
FROM 9 AM TO 11 AM, ALL THE MACHINES WERE OPERATING.
IE, THEY ALL OPERATED FOR 2 HOURS AND WORK COMPLETED = 2 × (37/120) = 37/60
PENDING WORK = 1- 37/60 = 23/60
HOURS TAKEN BY Q AN R TO COMPLETE THE PENDING WORK = (23/60) / (11/60) = 23/11
WHICH IS APPROXIMATELY EQUAL TO 2
HENCE THE WORK WILL BE COMPLETED APPROXIMATELY 2 HOURS AFTER 11 AM ; IE AROUND 1 PM
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WORK DONE BY P IN 1 HOUR = 1/8
WORK DONE BY Q IN 1 HOUR = 1/10
WORK DONE BY R IN 1 HOUR = 1/12
WORK DONE BY P,Q AND R IN 1 HOUR = 1/8 + 1/10 + 1/12 = 37/120
WORK DONE BY Q AND R IN 1 HOUR = 1/10 + 1/12 = 22/120 = 11/60
FROM 9 AM TO 11 AM, ALL THE MACHINES WERE OPERATING.
IE, THEY ALL OPERATED FOR 2 HOURS AND WORK COMPLETED = 2 × (37/120) = 37/60
PENDING WORK = 1- 37/60 = 23/60
HOURS TAKEN BY Q AN R TO COMPLETE THE PENDING WORK = (23/60) / (11/60) = 23/11
WHICH IS APPROXIMATELY EQUAL TO 2
HENCE THE WORK WILL BE COMPLETED APPROXIMATELY 2 HOURS AFTER 11 AM ; IE AROUND 1 PM
Was this answer helpful ?
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