1. For the following sample of the number of telephones sold in 10 days in a shopping center: 20, 18, 19, 12, 5, 44, 16, 23, 30, 27 a) Find the mean, median and mode. b) Find the variance and standard deviation (write the formula). What would happen to the variance value if the data set represented a population? c) Construct a box plot.

2. There are four flights daily from London to Brussels. Suppose that the probability that any flight arrives late is 0.08. Let X be a binomial variable that refers to the number of planes that arrive late. a) Find the mean and the standard deviation. b) What is the probability that exactly one of the flights is late? c) What is the probability that more than one flight will be late?

3. The average credit card debt for college seniors is $3100. If the debt is normally distributed with a standard deviation of $900, find these probabilities that the senior owes. a. At least $1800 b. Less than $4300 c. Between $2596 and $4999 Note: Represent graphically the above situations.

4. The owner of a gas station would like to estimate the mean number of gallons of gasoline sold. Assume the number of gallons sold follows the normal distribution with a population standard deviation of 7.25 gallons. A random sample of 33 customers revealed a mean number of gallons sold to be 24.5. a) Develop a 99% confidence interval for . b) How large a sample is needed to be within 2 gallons marge of error?