1.

According to the National Association of Childcare Resources and Referral Agencies, the average cost of care for an infant in a child-care center in Delaware was $8,769 a year. Assume this cost follows a normal distribution with a standard deviation of $925. a. What is the probability that a randomly selected child-care center in Delaware costs 1. more than $8,000 per year for infant care? 2. more than $9,000 per year for infant care? 3. between $8,500 and $9,500 per year for infant care? b. Use Excel to confirm the answers in part a. c. Determine the rate a child-care center that wishes to be in the 60th percentile in the state of Dela-ware should charge for an infant.

2.

Assume that the number of miles a particular brand of tire lasts before it needs to be replaced follows a normal distribution with a mean of 45,600 miles and a standard deviation of 5,800 miles. a. What is the probability that the next tire of this brand sold will last 1. more than 36,000 miles before it needs to be replaced? 2. less than 42,000 miles before it needs to be replaced? 3. between 45,000 and 55,000 miles before it needs to be replaced? b. Use Excel to confirm the answers in part a. c. What is the mileage that 90% of the tires of this brand will survive before needing to be replaced?