The lifetime of a certain type of automobile tire (in thousands of miles) is normally distributed with a mean of 39 and a standard deviation of 3.5. Find the following probabilities, round to the...

Extracted text: The lifetime of a certain type of automobile tire (in thousands of miles) is normally distributed with a mean of 39 and a standard deviation of 3.5. Find the following probabilities, round to the fourth. a) What is the probability 18 randomly chosen tires have an average lifetime greater than 38 0.8873 Would it be unusual or usual for this to happen? usual b) What is the probability 11 randomly chosen tires have a lifetime less than 32 Would it be unusual or usual for this to happen? unusual