The standard hemoglobin reading for normal males of adult age is 15 g/100 ml. The standard deviation is about 2.5 g/100 ml. For a group of 36 male construction workers, the sample mean was 16 g/100 ml.

a. Construct a 95% confidence interval for the male construction workers.

What is your interpretation of this interval relative to the normal adult male population?

b. What would the confidence interval have been if the above results were obtained based on 49 construction workers?

c. Repeat b for 64 construction workers.

d. Do fixed-level confidence intervals shrink or widen as the sample size increases

(all other factors remaining the same)? Explain your answer.

e. What is the half-width of the confidence interval that you would obtain for 64 workers?