statistics
posted by tea .
According to internal testing done by the GetAGrip tire company, the mean lifetime of tires sold on new cars is 23,000 miles, with a standard deviation of 2500 miles.
a) If the claim by GetAGrip is true, what is the mean of the sampling distribution of for samples of size ? (2 pts)
b) If the claim by GetAGrip is true, what is the standard deviation of the sampling distribution of for samples of size ? (4 pts)
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? (6 pts)
Respond to this Question
Similar Questions

statistics
A maker of tires for cars has a multitude of data to support the fact that the lifetime of their tires follows a normal distribution with a mean of 42,100 miles and a standard deviation of 2,510 miles. Find the probability that a randomly … 
Statistics
A purchasing agent for a trucking company is shopping for replacement tires for their trucks from two suppliers. The suppliers' prices are the same. However, Supplier A's tires have an average life of 60,000 miles with a standard deviation … 
Statistics
A purchasing agent for a trucking company is shopping for replacement tires for their trucks from two suppliers. The suppliers' prices are the same. However, Supplier A's tires have an average life of 60,000 miles with a standard deviation … 
statistics
A local tire store suspects that the mean life of a new discount tire is less that 39,000 miles. To check the claim, the store selects randomly 18 of these new discount tires. When they are tested, it is found that the mean life is … 
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 … 
math
a tire manufacturer believes that the tread life of its tires are normally distributed and will lst an average of 60,000 miles with a standard deviation of 3,000 miles. sixtyfour randomly selected tires were tested and the average … 
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. … 
statistic
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 … 
Statistics
According to internal testing done by the GetAGrip tire company, the lifetime of tires sold on new cars is normally distributed with a mean of 23,000 miles, with a standard deviation of 2500 miles. If the claim by GetAGrip is true, … 
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 …