Part I: Multiple Choice 1. In a survey of several hundred college graduates with

Question

Part I: Multiple Choice 1. In a survey of several hundred college graduates with a degree in business, the linear regression equation relating overall GPA r and monthly starting salary y (in thousands of dollars) was 1.501z-0.572. Select the most accurate statement. (a) GPA and starting salary are slightly negatively correlated (b) For each 1.5 point increase in GPA monthly salary increases by about $572, on average. (c) For each 0.572 point increase in GPA monthly salary increases by about $1500, on average. (d) For each 1 point increase in GPA monthly salary increases by about $572, on average. (e) For each 1 point increase in GPA monthly salary increases by about $1500, on average. 2. In order to compare the performance of students in large enrollment and small enrollment sections, thirty-five students from large sections and thirty-five students from small sections of a freshman mathematics course were randomly sedocted. The mean and sample standard deviation of grades on the common final exam for the students from large sections were 728 and 7.4; for the students from small sections the mean and sample standard deviation were and 6.8. Assuming that the populations are normally distributed with equal standard deviations, a 90% confidence interval for the difference in the mean common final exam scores between students in the two types of sections is about (a) 2.5 ±2.20 (b) 2.5±2.79 (e) 2.5 ±3.39 (d) 2.5±1.67 (e) 2.5±0.28

Explanation / Answer

1) option E) is correct

by definition of beta coefficients

2)

Two-Sample T-Test and CI

Sample   N   Mean StDev SE Mean
1       35 75.30   6.80      1.1
2       35 72.80   7.40      1.3

Difference = (1) - (2)
Estimate for difference: 2.50
90% CI for difference: (-0.33, 5.33)

option b) is correct

3)

Two-Sample T-Test and CI: new, standard

Two-sample T for new vs standard

          N   Mean StDev SE Mean
new       5 79.40   2.07     0.93
standard 6 70.17   2.14     0.87

Difference = (new) - (standard)
Estimate for difference: 9.23
90% CI for difference: (6.89, 11.57)
T-Test of difference = 0 (vs ): T-Value = 7.23 P-Value = 0.000 DF = 9
Both use Pooled StDev = 2.1091

option B) is correct

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