In Chapter 1, we described graphically using a frequency distribution table and a histogram the time (in seconds) for a random sample of n = 110 employees to complete a particular task. Describe the data numerically based on the frequency distribution given in Table 1.7. The data is stored in the data file Completion Times.

a. Compute the mean using Equation 2.21.
b. Compute the variance using Equation 2.22.
c. Compare your answers to the mean and variance calculated in Exercise 2.23.

COMPLETION TIMES (IN SECONDS) 220 less than 230 230 less than 240 240 less than 250 250 less than 260 260 less than 270 270 less than 280 280 less than 290 290 less than 300 FREQUENCY PERCENT 4.5 7.3 11.8 20.0 29.1 11.8 13 10 6.4