7.3 A random sample of 10 economists produced the following forecasts for percentage unemployment rate in the next year:

4.4 4.2 3.7 3.9 4.4 3.9 3.7 4.0 4.1 4.0

a. The population mean

b. The population variance

c. The variance of the sample mean

d. The population proportion of economists predicting unemployment rate of at least 4.0%