Question: Researchers wished to know if they could conclude that two populations of infants differ with respect to the average ages at which they walked alone. Assuming that the age at which the infant walked alone is normally distributed for two populations with the same variance. The following data (ages in months) were collected:

Sample from population A: 9.5, 9.5, 10.5, 9.0, 10.0, 10.0, 13.0, 10.0, 13.5, 10.0, 9.5, 10.0

Sample from population B:

12.5, 9.5, 13.5, 13.5, 11.0, 14.0, 11.5, 9.5, 11.0, 13.5, 12.5

Construct a 95% confidence for the difference of average ages for population A and B.