## Question

(d) Calculate the t test statistic. Can you reject ρ = 0? (e) Use Excel’s function =TDIST(t,deg_freedom,tails) to calculate the two-tail p-value.

12.2 Part-Time Weekly Earnings ($) by College Students

Hours Worked (X) Weekly Pay (Y)

10 93

15 171

20 204

20 156

35 261

Instructions for Exercises 12.4–12.6: (a) Make a scatter plot of the data. What does it suggest about the correlation between X and Y? (b) Use Excel, MegaStat, or MINITAB to calculate the correlation coefficient.

(c) Use Excel or Appendix D to find t.05 for a two-tailed test. (d) Calculate the t test statistic.

(e) Calculate the critical value of rα. (f) Can you reject ρ = 0?

12.4 Moviegoer Spending ($) on Snacks

Age (X) Spent (Y)

30 2.85

50 6.50

34 1.50

12 6.35

37 6.20

33 6.75

36 3.60

26 6.10

18 8.35

46 4.35

12.6 Number of Orders and Shipping Cost ($)

Orders (X) Ship Cost (Y)

1,068 4,489

1,026 5,611

767 3,290

885 4,113

1,156 4,883

1,146 5,425

892 4,414

938 5,506

769 3,346

677 3,673

1,174 6,542

1,009 5,088

12.8 (a) Interpret the slope of the fitted regression Sales = 842 − 37.5 Price. (b) If Price = 20, what is the prediction for Sales? (c) Would the intercept be meaningful if this regression represents DVD sales at Blockbuster?

12.10 The regression equation NetIncome = 2,277 + .0307 Revenue was fitted from a sample of 100 leading world companies (variables are in millions of dollars). (a) Interpret the slope. (b) Is the intercept meaningful? Explain. (c) Make a prediction of NetIncome when Revenue = 1,000.

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