Posted by **Eric** on Friday, April 27, 2012 at 8:43pm.

Tara is researching the stork population living in a bird reserve. On her first day, she captures and tags 37 birds. Two weeks later, she captures 48 birds and finds that 30 are not tagged. Estimate the actual number of storks in the bird reserve.

27. In a marketing survey involving 910 randomly chosen people, it is found that 550 use brand P, 360 use brand Q, and 90 use both brands. How many people in the survey use brand Q and not brand P?

- MATH URGENT!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! -
**MathMate**, Friday, April 27, 2012 at 9:40pm
a.

This is a typical case of a hypergeometric distribution where

Suppose

N=total population, (unknown)

n=sample size (48)

a=total number of tagged birds (37)

x=number (18) of tagged birds out of n (48)

Then approximately,

x/n = a/N

or

N=an/x = 37*48/18 = 99 (approximately).

b.

Q\P=Q-Q∩P=360-90=370

- MATH URGENT!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! -
**Kati**, Monday, May 7, 2012 at 11:30pm
The first question is 98.6666666, but if it is for a test, put "approximately 99".

The second question's answer is 270.

- MATH URGENT!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! -
**Anonymous**, Monday, May 21, 2012 at 12:30pm
i think the second answer is 315 because not all 90 people use brand Q. so take 90 divide by 2 then subtract.+

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