Use the information from the survey. Assume that "number of sales calls" is the independent variable, and draw a scatter diagram of number of sales calls and number of units sold. Estimate a simple linear regression model to explain the relationship between number of sales calls and number of units sold. Calculate and interpret the coefficient of correlation, the coefficient of determination, and the standard error of estimate. Conduct a test of hypothesis to determine whether the coefficient of correlation in the population is zero. Construct and interpret confidence intervals and prediction intervals for the dependent variable, number of units sold.