An NHANES report gives data for 642 women aged
20
–
29
years. The BMI of these
642
women was
¯
x
=

26.6
. On the basis of this sample, we want to estimate the BMI
μ
in the population of all
20.6
million women in this age group. We treated these data as an SRS from a Normally distributed population with standard deviation
σ
=
7.9
.
(a) Give three confidence intervals for the mean BMI
μ
in this population, using
90
%
,
95
%
,
and
99
%
confidence.