statistic
posted by HN
one of the major U.S. tire makers wishes to review its warranty for their rainmaker tire. The warranty is for 40,000 miles. The tire company beleives that the tire actually lasts more than 40,000 miles. A sample of 49 tires reveales that the mean number of miles is 45,000 miles with a standard deviation of 15,000 miles. Test the hypothesis with a 0.05 significance level. what are the null and alternative hypotheses for this study? what is the critical value for this this?

PsyDAG
Ho: sample mean = warranty mean
Ha: sample mean > warranty mean
Z = (sample mean  warranty mean)/standard error (SE) of difference between means
SEdiff = √(SEmeanS^2 + SEmeanW^2)
SEm = SD/√n
If only one SD is provided, you can use just that to determine SEdiff.
Find table in the back of your statistics text labeled something like "areas under normal distribution" to find the proportion/probability related to the Z score.
Respond to this Question
Similar Questions

Statistics
Wrong tire pressure can increase tire wear and decrease gas mileage. A manufacturer of new tires tested the tire for wear at different pressures with the below results. Tire pressure (PPI:pounds per square inch) is related to how many … 
Physics
The warranty on a new tire says that an automobile can travel for a distance of 92,000km before the tire wears out. The radius of the tire is 0.33m. How many revolutions does the tire make before wearing out? 
Math
Many tires come with 13/32 inch of tread. The first 2/32 inch wears off quickly(say during the first 1000miles). From then on the tire wears uniformly. A tire is considerd "worn out" when on 2/32 inch of tread is left. a. how many … 
statistics
Assume that Acme Tires sells their high performance tires for $180 each and their all weather tires for $135 each. Further assume that the cost of producing a high performance tire is $150 and the cost of producing an all weather tire … 
math
The tread life of a particular tire is a random variable best described by a normal distribution with a mean of 60,000 miles and a standard deviation of 2000 miles. What is the probability that a randomly selected tire of this brand … 
Geometry check my answer?
The diameter of a car tire is approximately 0.6meters. The warranty is good for 70,000 km. About how many revolutions will the tire make before the warranty is up? 
statistics
one of the major U.S. tire makers wishes to review its warranty for their rainmaker tire. The warranty is for 40,000 miles. The tire company beleives that the tire actually lasts more than 40,000 miles. A sample of 49 tires reveales … 
STATS
The top selling Red and Voss tire is rated 70,000 miles means nothing. In fact, the distance the tires can run until they wear out is a normally distributed random variable with a mean of 82,000 miles and a standard deviation of 6,400. … 
Behavioral Statistics
I need someone to explain HOW to do this..I don't want just the answer I have got to figure out how to do this before my midterm, and I'm completely clueless! 3. One of the major U.S. tire makers wishes to review its warranty for … 
physics
Tires on a car have a diameter of 2 ft and are warranted for 60 000 miles. a) Determine the angle (in radians) through which one of these tires will rotate during the warranty period. b) How m,any revolutions of the tire are equivalent …