In an article in the American Psychologist by Sandra Scarr and Richard A. Weinberg (August, 1976) entitled "IQ Test Performance of Black Children Adopted by White Families," the IQ scores of natural...

In an article in the American Psychologist by Sandra Scarr and

Richard A. Weinberg (August, 1976) entitled "IQ Test Performance

of Black Children Adopted by White Families," the IQ scores of

natural and adopted children were reported. The results showed

the average Stanford-Binet IQ of the 48 natural children was

x1 = 113.8 with s1 = 16.7 and the average IQ for 122 adopted

children was x2 = 106.5 with s2 = 13.9.

(a) Do the data indicate a significant difference between these

two groups (a = 0.05)?

(b) Find a 95% confidence interval for µ1 - µ 2•