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 1,750 225
2 1,000 234
3 1,250 281
4 750 208
5 1,750 90
6 1,250 213
7 1,250 158
8 1,750 216
9 1,500 255
10 1,250 220
11 1,250 108
12 1,750 208
13 2,000 89
14 1,500 266
15 2,000 262
16 1,000 61
17 1,500 166
18 750 284
19 1,250 199
20 600 50
a. Compute the correlation between the wattage and heating area. Is there a direct or an indirect relationship? (Round your answer to 4 decimal places.)
b. Conduct a test of hypothesis to determine if it is reasonable that the coefficient is greater than zero. Use the 0.100 significance level. (Round intermediate calculations and final answer to 3 decimal places.) H0: Ļ ā¤ 0; H1: Ļ > 0 Reject H0 if t > 1.330
c. Develop the regression equation for effective heating based on wattage. (Negative value should be indicated by a minus sign. Round your answers to 3 decimal places.)
d. What heating area corresponds with a 1,500-watt heater? (Round your answers to 4 decimal places.)
e. What is the 95% confidence interval of heating the area if the wattage is 1,500? (Round your answers to 4 decimal places.)
