The data shows the relationship between the number free samples of hair conditioner given away by manufacturer by the number of orders made as a result. There is a linear relationship of the form y=a+bx (the regression equation), between the number of calls (=x) and the sales (=y) with = intercept, b= gradient of the line.

Sample(n) free samples given orders (y)

1. 72 3200

2. 66 3000

3. 62 3500

4. 193 4000

5. 220 4700

6. 234 5000

7. 278 6000

8. 290 6500

9. 322 6500

10. 345 7000

Totals 2082 49400

a) use the data from total row to calculate the gradient b (order per free sample) of the regression line.

b) calculate the intercept, a, of the regression line (orders).

c) calculate the coefficient of determination r^{2 of the data set?}