6, Is smoking during pregnancy associated with premature births?
To investigate this question, researchers selected a random sample
of 132 pregnant women who were smokers. The average pregnancy
length for this sample of smokers was 265 days. From a large body
of research, it is known that length of human pregnancy has a
standard deviation of 16 days. The researchers assume that smoking
does not affect the variability in pregnancy length.
Find the 90% confidence interval to estimate the length of
pregnancy for women who smoke.
(Note: The critical z-value to use, zc, is:
1.645)
Your answer should be rounded to 3 decimal places.