Suppose IQ scores were obtained from randomly selected twins

Suppose IQ scores were obtained from randomly selected twins. For 20 such pairs of people, the linear correlation coefficient is 0.917 and the equation of the regression line is y=20.63+1.19x, where x represents the IQ score of the twin born first. Also, the 20 x values have a mean of 104.29 and the 20 y values have a mean of 103.2. What is the best predicted IQ of the twin born secondtwin born second, given that the twin born first has an IQ of 100? Use a significance level of 0.05.

The best predicted IQ of the twin born secondtwin born second is

(Round to two decimal places as needed.)

Solution

The best predicted IQ of the twin born secondtwin born second is calculated using the regression equation,

with X = 100:

y = 20.63+1.19*100 = 98.37