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per capita income

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per capita income

by dikku07 » Thu Sep 24, 2009 10:44 am
In a demographic study, the population and total income of a certain region were estimated from other data, and both estimates had lower and upper limits. At the time of the estimates, was the per capita income for the region greater than $16,500?

(1) The lower limit for the estimate of the population was 330,000 people.
(2) The lower limit for the estimate of the total income was $5,500,000,000.


kindly explain.
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by grockit_jake » Thu Sep 24, 2009 3:34 pm
Since the question is asking for "is the per capita income GREATER", then it helps to find a LOWER bound. If we find the minimum possible per capita income, then we know all other options are above it.

We would minimize per capita income by minimizing Income and MAXIMIZING the number of people.

Since we only have lower bounds, we should use those and see what direction additional information will move us in

5,500,000,000 / 330,000 =

550,000 / 33 =

50,000 / 3 = 16,667 > 16,500. However, because population can rise above the lower limit, the per capita can decrease. By not knowing the upper bound, we don't have enough info. (E)
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by dikku07 » Sat Sep 26, 2009 6:39 am
Thanks for the explanation.
OA is E

now I understand why do we need upper limit too to find least value..
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