Question

In a sample of 150 cars, 18 cars failed a safety inspection. The sampling method had a margin of error of 0.02

What is the interval estimate for the proportion that would fail in the form

(lower limit, upper limit)?

Answer 1

(0.10, 0.14)

Explanation:

Answer 2

(Lower limit, Upper limit) = (0.10, 0.14)

(Lower limit, Upper limit) = (10%, 14%)

Step-by-step explanation:

Total number of cars = 150

Cars that failed the safety inspection = 18

The proportion is given by

p = 18/150

p = 0.12

p = 12%

The confidence interval is given by

p ± margin of error

Where margin of error is 0.02

0.12 ± 0.02

Lower limit = 0.12 - 0.02

Lower limit = 0.10

Lower limit = 10%

Upper limit = 0.12 + 0.02

Upper limit = 0.14

Upper limit = 14%

(Lower limit, Upper limit) = (0.10, 0.14)

(Lower limit, Upper limit) = (10%, 14%)