52.
If 9 examiners can examine a certain number of answer books in 12 days, working
5 hours a day; for how many hours a day would 4 examiners have to work in order
to examine twice the number of answer books in 30 days?
[A]
6
[B]
8
[C]
9
[D] 10
Answer : C
Explanation :
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Let
the required number of working hours per day be x.
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Less
examiners, More working hours per day (Indirect Proportion)
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More
days, Less working hours per day (Indirect Proportion)
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More
answer books, More working hours per day (Direct Proportion)
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Examiners
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4
: 9
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Days
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30
: 12
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Answer
books
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1
: 2
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::
5 : x
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(4
x 30 x 1 x x) = (9 x 12 x 2 x 5)
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