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AVERAGE

by grandh01 » Sun Aug 12, 2012 5:34 pm
What was the average (arithmetic
mean) monthly rainfall during 1984 in
region Y?
(1) In region Y the total rainfall for the
first 6 months of 1984 was twice
the total rainfall for the last 6
months of 1984.
(2) In region Y the average monthly
rainfall for the first 6 months of
1984 was 2.31 inches more than
the average monthly rainfall for
the last 6 months of 1984.

OA is C
Last edited by grandh01 on Tue Aug 14, 2012 1:05 pm, edited 1 time in total.
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Source: — Data Sufficiency |
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by adthedaddy » Sun Aug 12, 2012 11:47 pm
Hi,
I would solve this way.

Let the rainfall for first six months be 'x' & for the next six months be 'y'.
(1) The eqn becomes x=2y
NOT SUFFICIENT as we do not get any further information

(2) x/6 - y/6 = 2.31 => x-y=13.86
NOT SUFFICIENT as you cannot simplify further

Taking (1) & (2) combined,

We can substitute x=2y from (1) into (2), we get

2y-y=13.86
=> y=13.86

Thus we get a unique difinite value.

Ans: C
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