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Source: — Data Sufficiency |
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by eaakbari » Thu Apr 01, 2010 11:07 am
IMO D
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by eaakbari » Thu Apr 01, 2010 11:12 am
Stem
To find average daily balance we need to find the day Jane made the payment. Let x be the number of days before the payment and y number of days after payment

(600x + 300y)/30 = average


Statement one
Tells us the date of payment so we can find average hence suff

Statement two
Tells us the average till the 25th

We can set the equations
600x + 300(y-5) = 540
x +y = 30
we can find x and y
Hence suff

Therefore answer is D
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by neoreaves » Thu Apr 01, 2010 11:23 am
what we need to know is the daily average lets say x = ?

1) we know that from day 1 to day 20 the daily balance was 600 and then from 21 to 30 it was 300
so the average should be 500
SUFFICIENT

2) the average through 25th day means from day 1 to day 25 the average was 540

540 = (600n + 300(25-n) ) /25

n = 20

so from this we can find x
SUFFICIENT
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