(2) Suppose that a certain brand of tires is good for a mean of 40,000 miles with a standard deviation of 5000 miles, also suppose that the population of this brand is normal. What is the percentage...

I need help with question 3. When it talks about question 1 it’s actually referring to question 2 which is also in the pic.

Extracted text: (2) Suppose that a certain brand of tires is good for a mean of 40,000 miles with a standard deviation of 5000 miles, also suppose that the population of this brand is normal. What is the percentage of tires that last at least 35,000 miles? (3) In problem 1, suppose that the tire company guarantees tires to last at lest 30,000 miles, and will replace any tire that does not last this long. a) What percentage of tires will have to be replaced? b) If the cost of such a replacement is $86, how much will the company expect to pay on each lot of 1000 tires?