he accompanying data were read from graphs that appeared in an article. The variables shown are the number of acres burned in forest fires in the western United States and timber sales. Year Number of Acres Burned (thousands) Timber Sales (billions of board feet) 1945 210 2.2 1950 260 3.9 1955 251 4.6 1960 371 6.8 1965 78 9.7 1970 460 11.1 1975 176 11.0 1980 246 10.1 1985 449 9.9 1990 401 11.1 1995 183 3.8 (a) Compute the correlation coefficient. (Give the answer to three decimal places.) r =
x | y | (x-Mx)^2 | (Y-My)^2 | (X-Mx)(Y-My) |
210 | 2.2 | 4963.907025 | 29.757025 | 384.332025 |
260 | 3.9 | 418.407025 | 14.100025 | 76.808525 |
251 | 4.6 | 867.597025 | 9.333025 | 89.985025 |
371 | 6.8 | 8198.397025 | 0.731025 | -77.415975 |
78 | 9.7 | 40988.02703 | 4.182025 | -414.020475 |
460 | 11.1 | 32236.40703 | 11.868025 | 618.532525 |
176 | 11 | 10910.84703 | 11.189025 | -349.401975 |
246 | 10.1 | 1187.147025 | 5.978025 | -84.242475 |
449 | 9.9 | 28407.41703 | 5.040025 | 378.383525 |
401 | 11.1 | 14531.09703 | 11.868025 | 415.277525 |
183 | 3.8 | 9497.477025 | 14.861025 | 375.689025 |
Sum=3085 | 84.2 | 152206.727 | 118.907 | 1413.927 |
mean=280.45 | mean=7.655 |
r=0.332
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