Question

Coffee is a leading export from several developing countries. When coffee prices are high, farmers often clear forest to plant more coffee trees. Here are data on prices paid to coffee growers in Indonesia and the rate of deforestation in a national park that lies in a coffee-producing region for five years: Price(cents per pound) Deforestation (percent) 29 0.49 40 1.59 54 1.69 55 1.82 72 3.10

(a) Make a scatterplot. What is the explanatory variable? What kind of pattern does your plot show? (b) Find the correlation r step-by-step. That is, find the mean and standard deviation of the two variables. Then find the five standardized values for each variable and use the formula for r. Explain how your value for r matches your graph in (a). (c) Now enter these data into your calculator or Excel and use the correlation function to find r. Check that you get the same result as in (b).

Answer 1

x: Price(cents per pound)

y: Deforestation (percent)

a) Price per pound is the explanatory variable & deforestation is response variable

Scatter plot

From the plot, we can conclude the strong positive correlation between the  Price(cents per pound) & Deforestation (percent).

sr no	x	y	x^2	y^2	xy
1	29	0.49	841	0.24	14.21
2	40	1.59	1600	2.53	63.60
3	54	1.69	2916	2.86	91.26
4	55	1.82	3025	3.31	100.10
5	72	3.1	5184	9.61	223.20
Total	250	8.69	13566	18.55	492.37
mean = total / 5	50	1.738	2713.2	3.71	98.47