In a sample of 77 children, the mean age at which they first began to combine words was 16.51 months, with a standard deviation of 9.59 months.

a. Construct a 95% confidence interval for the mean age at which children first begin to combine words.

b. If a sample of 50 children had been studied, would you expect the confidence interval to be wider or narrower than the interval constructed in part (a)? Explain.