1. The average age of a Canadian University professor is 4545 years, with a standard deviation of 99 years. The average yearly salary of these professors is $85,000$85,000 with a standard deviation of $10,000$10,000. Does age have more variation (relative to the mean) as compared to salary? Justify.

2. Suppose that 60% of all customers of a large cable company subscribe to Internet service, 40% subscribe to phone service, and 25% have both types of services. If a customer is selected at random, what is the probability that the customer

(a) has either internet service or phone service?

(b) has neither of these services?

(c) has exactly one of these two services?

3. A random sample of 781 individuals showed that 15% do not have any health insurance. Based on this sample data answer the following:

• What is the 97% confidence interval to estimate the true proportion of individuals who do not have health insurance?
• Using the most conservative estimate, what minimum possible sample size is needed to maintain the margin of error 0.02 and 95% confidence level?

4. A recent study of 2525 students showed that they spent an average of $18.53 on gasoline per week. The standard deviation of the sample was $3.00$3.00. Assuming that weekly gasoline expenditures are normally distributed, find a 98% confidence interval for the mean amount spent on gasoline per week by all students and interpret the result.