A company that owns and services a fleet of cars for its sales force has found that the service lifetime of disc brake pads varies from car to car according to a normal distribtion with mean = 55900 miles and standard deviation = 4675 miles. The company installs a new brand of brake pads on 13 cars. a.) If the new brand has the same lifetime distribution as the previous type, what is the distribution of the sample mean lifetime for the 13 cars? Mean = __________miles Standard Deviaiton =______________miles b.) The average life of the pads on these 13 cars turns out to be xbar=52300 miles. What is the probability that the sample mean lifetime is 52300 miles or less if the lifetime distribution is unchanged? (The company takes this probability as evidence that the average lifetime of the new brand of pads is less than 55900 miles.)
A company that owns and services a fleet of cars for its sales force has found that the service lifetime of disc brake pads varies from car to car according to a normal distribtion with mean = 55900 miles and standard deviation = 4675 miles. The company installs a new brand of brake pads on 13 cars.
a.) If the new brand has the same lifetime distribution as the previous type, what is the distribution of the sample mean lifetime for the 13 cars?
Mean = __________miles
Standard Deviaiton =______________miles
b.) The average life of the pads on these 13 cars turns out to be xbar=52300 miles. What is the probability that the sample mean lifetime is 52300 miles or less if the lifetime distribution is unchanged? (The company takes this probability as evidence that the average lifetime of the new brand of pads is less than 55900 miles.)
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