Iron-deficiency anemia is an important nutritional health problem in the United States. A dietary assessment was performed on 51 boys 9 to 11 years of age whose families were below the poverty level....

Iron-deficiency anemia is an important nutritional health
problem in the United States. A dietary assessment was
performed on 51 boys 9 to 11 years of age whose families
were below the poverty level. The mean daily iron intake
among these boys was found to be 12.50 mg with standard
deviation 4.75 mg. Suppose the mean daily iron intake
among a large population of 9- to 11-year-old boys from
all income strata is 14.44 mg. We want to test whether the
mean iron intake among the low-income group is different
from that of the general population.

The standard deviation of daily iron intake in the larger pop-
ulation of 9- to 11-year-old boys was 5.56 mg. We want to test whether the standard deviation from the low-income group is comparable to that of the general population.
Problem a) State the hypotheses that we can use to answer this
question.

Problem b) Carry out the test in Problem a using the critical-
value method with an α level of 0.05, and summarize your findings.

Problem c) What is the p-value for the test conducted in ­Problem
b?

Problem d) Compute a 95% CI for the underlying variance of
daily iron intake in the low-income group. What can you
infer from this CI?

Problem e) Compare the inferences you made from the proce-
dures in Problems b, Problem c and Problem d.