Twenty plots, each 10x4 meters, were randomly chosen in a large field of corn. For each plot, the plant density (number of plants in the plot) and the mean cob weight (gm of grain per cob) were observed. The results are given in the table.8

Preliminary calculations yield the following results:
x = 128.05 = 224.10 sx = 32.61332 sy = 24.95448 r = -0.94180
(a) Is there significant evidence for a linear relationship between cob weight and plant density? Carry out an appropriate test using a = 0.05.
(b) Is this study an observational study or an experiment?
(c) Farmers are interested in whether manipulating plant density can alter cob weight. Could these data be used to answer this question? If not, what could be said? Briefly explain.

Transcribed Image Text:

Cub igh n 194 41 196 193 220 250 200 190 008 220 163470 1211 212 2 012 201 ais 125 250 201 202 200 196 017266 But X-197 07 102 195 15 103 02 65 49 85