Time and Work Practice Test 5 with solutions

Question : 16 of 30

Marks: +1, -0

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 machine complete the work. Approximately at what time will the work be finished?

1 p.m.
12.30 p.m.
12 noon
11.30 a.m.

Validate

Solution:

In 2 hours machine P will print 1 lakh ×

2/8

= 20,000 books
Remaining number of books = 1,00,000 – 20,000 = 80,000 books
which will be printed by machines Q and R
Machines (Q + R)'s 1 hour's work =

(1/{10}+1/{12}) × 100000

{11}/{60} × 100000

{55000}/3

books
Hence, time taken by both the machines to print the remaining books =

{80000}/{{55000}/3}

{80000×3}/{55000}

= 4.36 hrs. = 4 hrs.
Therefore, required time = 9 a.m. + 4 hrs. = 1 p.m.

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