A book publisher charges its clients based on the number of pages that are printed. The table below shows the number of pages printed of the last six books and the cost of the items: Price ($) 143 179 197 335 384 423 Number of pages 42 50 47 58 57 73 a. Decide which variable should be the independent variable and which should be the dependent variable. Justify your decision. b. Compute ∑ X , ∑X 2, ∑ Y, ∑Y 2 and ∑ XY c. Find and interpret the slope of the regression line. d. Find and interpret the intercept of the regression line. e. Write down the regression equation. f. Find and interpret the coefficient of determination.
A book publisher charges its clients based on the number of pages that are printed. The table below
shows the number of pages printed of the last six books and the cost of the items:
Price ($) | 143 | 179 | 197 | 335 | 384 | 423 |
Number of pages | 42 | 50 | 47 | 58 | 57 | 73 |
a. Decide which variable should be the independent variable and which should be the
dependent variable. Justify your decision.
b. Compute ∑ X , ∑X 2, ∑ Y, ∑Y 2 and ∑ XY
c. Find and interpret the slope of the regression line.
d. Find and interpret the intercept of the regression line.
e. Write down the regression equation.
f. Find and interpret the coefficient of determination.
g. Use the 10% level of significance to examine whether the independent variable is a good
predictor for the dependent variable. In responding, state the null hypothesis(es), the
decision rule and make the decision for each hypothesis.
h. Would the simple regression be useful in predicting price given the number of pages of 90?
In responding, state the null hypothesis(es), the decision rule for α = 0.05 and make the
decision for each hypothesis.
i. Find and interpret a 90% confidence interval for the slope of the regression line.
j. Find and interpret a 95% confidence interval for the price when the pages are $50.
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