Approximately 20 of cars in the US are white You take an SRS

Approximately 20% of cars in the US are white. You take an SRS of 300 cars parked in student lots on your campus and find 42 are white. For this problem, you can assume that you have obtained an SRS of student cars on campus.

a) what is the proportion, p^, of white cars in your sample?

b) If 20% of student cars on campus are white, what proportion of samples wpuld give a value of p^ as small as the value computed in (a)?

c) There are two explanations for your sample result. The first is that you obtained a sample with an unusually low percentage of white cars. What is an alternative explanation?

Solution

a)

42 / 300 = 0.14

b)

0.20*300 = 60

c)

the other alternative is that you obtained a sample very big that have a lot of white cars