Question

(CO 5) An advocacy group claims that the mean braking distance of a certain type of tire is 75 feet when the car is going 40 miles per hour. In a test of 45 of these tires, the braking distance has a mean of 78 and a population standard deviation of 5.9 feet. Find the standardized test statistic and the corresponding p-value. Group of answer choices

Answer 1

z=0.5084

p=0.2809

Explanation:

Since number of tires tested for breaking distance is enough (>30), the standardized test statistic is calculated by the formula:

z=
`(X-M)/((s)/(√(N) )) }` where

• X is the mean breaking distance in the sample (78)
• M is the mean breaking distance (75)
• s is the standard deviation (5.9)
• N is the sample size

Putting the numbers in the formula:

z=
`(78-75)/((5.9)/(√(N) )) }` =0.5084 and corresponding p value is:

p=0.28