The eggs of a species of bird have an average diameter of 23 mm and an SD of 0.45 mm. The weights of the chicks that hatch from these eggs have an average of 6 grams and an SD of 0.5 grams. The correlation between the two variables is 0.75 and the scatter diagram is roughly football shaped.

Question

The slope of the regression line for estimating chick weight based on egg diameter is

0.833 inches per gram
0.675 inches per gram
0.833 grams per mm
0.675 grams per mm

The intercept of the regression line for estimating chick weight based on egg diameter is _______________ grams.

Answer 1

0.833 grams per mm

Answer 2

That answer is incorrect.

Answer 3

0.833 inches per gram

Answer 4

They are all wrong.

Answer 5

0.833 grams per mm is correct:

slope=rsd(y)/sd(x)=0.75*0.5/0.45
slope is 0.8333 grams per mm

The intercept of the regression line for estimating chick weight based on egg diameter is

Intercept=mean y - slope *mean x
Intercept = 23 - 0.8333* 6 = 18