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.

Question

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?

Answer 1

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

Answer 2

The first question is 98.6666666, but if it is for a test, put "approximately 99".

The second question's answer is 270.

Answer 3

i think the second answer is 315 because not all 90 people use brand Q. so take 90 divide by 2 then subtract.+