For all Hypothesis Test Questions you must: 1) state both the null and alternati

Question

For all Hypothesis Test Questions you must: 1) state both the null and alternative hypotheses 2) state which test or test statistic you are using 3) state EITHER the p-value and the alpha value (if you are using the p-value approach) OR the test statistic value and critical value(s) (if you are using the classical approach) 4) state your conclusion (i.e. "There is sufficient evidence to support the claim that students who take note perform better on the test.")

Here is the week's Email Response Question:

A doctor suspects that male babies are born with higher birth weights than female babies. She take a simple random sample of 10 male babies and finds they have a mean weight of 7 pounds 11 ounces with a standard deviation of 8 ounces. She also takes a simple random sample of 8 female babies and finds they have a mean weight of 7 pounds 4 ounces with a standard deviation of 5 ounces. Does this sample data support the doctors claim at the alpha = 0.05 level of significance? [Assume that weights of babies are normally distributed.]

Explanation / Answer

Hypotheses:

H0:mu1-mu2=0 (there is no difference in mean birth weight of male and female babies)

H1:mu1-mu2>0 (mean birth weight of male babies is higher than female babies) .

Test statistic:

2-sample t test statistic (assume Independent samples assumption, independent assumption, Randomization condition and Nearly normal conditions are reasonably met)

At df=, and alpha=0.05, the t critical value is: 1.753

Test statistic:

t=(x1bar-x2bar)/SE(x1bar-x2bar)=(123-116)/sqrt[2.5^2/10+1.8^2/8]

=2.27

Conclusion: The test statistic falls in critical region, therefore, reject H0 to conclude that there is sufficient evidence to support the claim as made by the doctor.

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