A) A tire company manufactures tires with a mean life of 43,000 miles and a standard deviation of 3,900 miles. The company wants to issue a guarantee for the tires but does not want to replace more than 4% of the tires sold. How many miles should the tires be guaranteed for? (Hint, watch out for the sign of Z.)

B) If the company expects to sell 90,000 tires in a year, how many tires can the company expect to replace under the guarantee?