A consumer buying cooperative tested the effective heating area of 20 different electric space heaters with different wattages. Here are the results. Heater Wattage Area
1 1,500 86
2 2,000 129
3 1,250 161
4 2,000 224
5 2,000 82
6 2,000 99
7 750 80
8 1,250 228
9 2,000 282
10 1,000 50
11 2,000 279
12 1,500 179
13 1,500 206
14 750 44
15 1,250 150
16 1,250 293
17 1,500 228
18 1,000 222
19 1,000 106
20 1,750 187

Required:
a. Conduct a test of hypothesis to determine if it is reasonable that the coefficient is greater than zero. Use the 0.100 significance level.
b. Compute the correlation between the wattage and heating area. Is there a direct or an indirect relationship?
c. Develop the regression equation for effective heating based on wattage.
d. Which heater looks like the "best buy" based on the size of the residual?