SOLUTION: A manufacturer claims that the life span of its tires is 47,000 miles. You work for a consumer protection agency and you are testing these tires. Assume the life spans of the tires

Question 1043989: A manufacturer claims that the life span of its tires is 47,000 miles. You work for a consumer protection agency and you are testing these tires. Assume the life spans of the tires are normally distributed. You select 100 tires at random and test them. The mean life span is 46 comma 46,756 miles. Assume σ=700. Complete part A.
(a) Assuming the manufacturer's claim is correct, what is the probability that the mean of the sample is 46,756 miles or less? (Round to four decimal places as needed.)

Answer by Boreal(15235) (Show Source): You can put this solution on YOUR website!
z=(sample mean-postulated mean) divided by sigma/ sqrt (n)
This is
z=(46,756-47,000)/700/sqrt(100)
z=-244*10/700=-2440/700=-3.49
Probability z <-3.49 is 0.0002

RELATED QUESTIONS
A manufacturer claims that the life span of its tires is 51000 miles. You work for a... (answered by Boreal)

A manufacturer of a certain type of auto batteries claims that the mean life of batteries (answered by ewatrrr)

please help me answer these questions; Do the hypothesis testing to answer this... (answered by rothauserc)

The breaking strengths of cables produced by a certain company are approximately normally (answered by stanbon)

The breaking strengths of cables produced by a certain company are approximately... (answered by stanbon)

A light-bulb manufacturer claims that the light bulbs produced by his company have an... (answered by stanbon)

1. A tire manufacturer wishes to investigate the tread life of its tires. A sample of 10... (answered by CPhill)

The manufacturer of a particular all-season tire claims that the tires last for 22,000... (answered by stanbon)

Please,I really need some help with this problem: The manufacturer of Winston Tire... (answered by stanbon)