Part I: Multiple Choice 1. In a survey of several hundred college graduates with
ID: 3316455 • Letter: P
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±0.28Explanation / 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