A new study suggests that women with asthma exposed to air pollution, even before conception, significantly increase the

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A new study suggests that women with asthma exposed to air
pollution, even before conception, significantly increase their
risk of delivering a premature baby. The researcher reported
gestational ages for two groups of women with asthma – one group of
48 women exposed to air pollution (mean = 34 weeks with a standard
deviation of 1 week) and another group of 40 women not exposed to
air pollution (mean = 38 weeks with a standard deviation of 1
week). Which one of the following statements is INCORRECT? (Set
alpha level at 0.05; Pooled standard deviation = 1) Group of answer
choices
A. The null hypothesis is that gestational age is not different
between women with asthma who are exposed to air pollution and
those who are not exposed to air pollution.
B. The decision should be to reject the null hypothesis. The
degrees of freedom is 87.
C. The ratio of variances is 1.
D. The obtained test statistic is approximately -18.68.
E. The critical test statistic is 1.960.