The determinant coefficient r2 and comment on the result

Question

Question (1):

A jeans manufacturer knows that a large budget for television advertising (x) of his product will create a demand (y) for it among department store buyers. In a sample of eight years we obtain the following data.

∑x = 920

∑x² = 124500

∑y = 885

∑y² = 115075

The regression coefficient of y on x (b) = 0.94

Using the previous information calculate

(1) The correlation coefficient (r) and comment on the result.

(2) The determinant coefficient (R²) and comment on the result.

(3) Predict the demand (y) when the budget for television advertising (x) equals 10.

Question (2):

In a study of the relation between the experience (in years) (x) and the number of computers sold (y) during the last three months, we draw a sample of seven sales persons and obtain the following results

∑x_i = 63

∑y_i = 210

∑x_i y_i = 2084

∑y_i² = 6820

The correlation coefficient ( r ) = 0.89

Find:

a) Find the suitable least squares regression line.

b) Give a brief interpretation of the values of the Y-intercept and slope calculated in the previous part.

c) Calculate the determinant coefficient and interpret its value.

d) Predict the number of computers sold during the past three months by salespersons with twenty years experience.