A sample of Brand A of automobile tires has a mean lifespan of 35,000 miles and a standard deviation of 2,500 miles. Assume the lifespans of the tires have a bell-shaped distribution. a. Between what 2 values does 95% of all tires have for a lifespan?
b. What percentage of tires have a lifespan of 37,500 to 40,000 miles?
c. What is the z-value for a tire whose lifespan is 28,000?
d. If 50 more tires were added to the sample, how many would have a lifespan of
less than 32,500 miles?
e. If Brand B tires has a mean lifespan of 38,000 miles and a standard deviation of
6,000 miles, which brand would you choose, and why?