2. Old Faithful Use the data given below (from Table 10-1). The duration times are in seconds and the heights are in feet.

a. Is there a significant linear correlation between duration of an eruption of the Old Faithful geyser and the height of the eruption?

b. Find the equation of the regression line with height representing the response (y)

variable.

c. What is the best predicted height of an eruption that has a duration of 180 sec?

Duration 240 120 178 234 235 269 255 220 Height 140 110 125 120 140 120 125 150 Predicting Cost of Electricity. Given below are measurements from the author’s home taken from Data Set 9 in Appendix B. Use these data for Exercises 3–5.

kWh 3375 2661 2073 2579 2858 2296 2812 2433 2266 3128 Heating Degree Days 2421 1841 438 15 152 1028 1967 1627 537 26 Average Daily Temp 26 34 58 72 67 48 33 39 66 71 Cost 321.94 221.11 205.16 251.07 279.8 183.84 244.93 218.59 213.09 333.49

(dollars)