The Following Are Costs of Advertising (In Thousands of Dollars)

Multiple Choice

The following are costs of advertising (in thousands of dollars) and the numbers of products sold (in thousands) : $$\begin{array} { c | r r r r r r r r } \text { Cost } & 9 & 2 & 3 & 4 & 2 & 5 & 9 & 10 \\\hline \text { Number } & 85 & 52 & 55 & 68 & 67 & 86 & 83 & 73\end{array}$$ The equation of the regression line is ^y = 2.78846x + 55.7885. Find the coefficient of determination.

A) 0.2353
B) 0.5009
C) 0.7077
D) -0.0707