Mr. James McWhinney, president of Daniel-James Financial Services, believes there is a relationship between the number of client contacts and the dollar amount of sales. To document this assertion, Mr. McWhinney gathered the following sample information. The x column indicates the number of client contacts last month, and the y column shows the value of sales ($ thousands) last month for each client sampled. (Round the final answers to 2 decimal places.) y^2 xy 529 506 116 13, 456 5,336 3, 249 2, 109 35 1, 225 665 49 95 9, 025 4, 655 54 2, 916 1, 890 In ON 50 2, 500 1, 800 63 3, 969 2, 646 1, 681 1, 271 729 378 331 561 39, 279 21, 256 a. Determine the standard error of estimate. b. Suppose a large sample is selected (instead of just 10). About 68% of the predictions regarding sales would occur between what two values? Assuming that the Standard Error of Estimate does not change. Use z= 1. y't