According to Internal Testing Done by the Get-A-Grip Tire Company

question 22

Essay

According to internal testing done by the Get-A-Grip tire company, the mean lifetime of tires sold on new cars is 23,000 miles, with a standard deviation of 2,500 miles.
a) If the claim by Get-A-Grip is true, what is the mean of the sampling distribution of for samples of size n = 4?
b) If the claim by Get-A-Grip is true, what is the standard deviation of the sampling distribution of for samples of size n = 4?
c) If the distribution of tire life is approximately normal, what is the probability that the mean of a random sample of size n = 4 of tire lifetimes will be less than 20,000 miles?

---

Definitions:

Plantar Flexion

A movement of the foot that increases the angle between the shin and the top of the foot, as seen when standing on tiptoe.

Popliteus

A small muscle located at the back of the knee joint, crucial for initiating knee flexion.

Tibialis Posterior

A muscle in the leg that supports the arch of the foot and aids in walking by controlling plantar flexion and inversion of the foot.

Fibularis Brevis

A muscle of the lower leg that contributes to the eversion and plantarflexion of the foot.