Question

The 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	207	2.1
1950	255	3.9
1955	259	4.6
1960	370	6.7
1965	86	9.9
1970	440	11.1
1975	190	11.1
1980	234	10.2
1985	443	10.2
1990	405	11.2
1995	184	3.7

(a) Compute the correlation coefficient. (Give the answer to three decimal places.)

r=

please show work. thank you.

Answer 1

Independent variable (x): Number of Acres Burned

Dependent variable (y): Timber Sales

Following table shows the calculations:

	X	Y	X^2	Y^2	XY
	207	2.1	42849	4.41	434.7
	255	3.9	65025	15.21	994.5
	259	4.6	67081	21.16	1191.4
	370	6.7	136900	44.89	2479
	86	9.9	7396	98.01	851.4
	440	11.1	193600	123.21	4884
	190	11.1	36100	123.21	2109
	234	10.2	54756	104.04	2386.8
	443	10.2	196249	104.04	4518.6
	405	11.2	164025	125.44	4536
	184	3.7	33856	13.69	680.8
Total	3073	84.7	997837	777.31	25066.2

Sample size: n =11

Now,

The coefficient of correlation is :

(d)

For this we need part c.