Question 7

The descriptive statistics of ages (in days) at the time of death for samples of 11 girls and 16 boys who died of sudden death syndrome are given in the table below. Do these indicate a gender difference? Use a significance level of 0.05. Assume variances are equal and the distributions are normally distributed.

	Females	Males
n	11	16
mean	107.64	97.75
std dev	66.132	60.45

a) What is the sign, in words, of the alternative hypotheses (answer with either less/greater/not equal)?

b) In this problem should you use the pooled variance (pv) or should you approximate the degrees of freedom with Welch's approximation (df)(answer with either pv/df)?

c) Depending on what you answered for b), what is the pooled variance, rounded to 4 decimal places, or the Welch's approximate degrees of freedom, given with no decimal places?

d) Is this a T test or Z test (answer with either T or Z only)?

e) What is the value of the test statistic, rounded to 4 decimal places?

f) If you could graph the p-value region, how many sides of the graph should be shaded (answer with 1 or 2)?

g) If the p-value=0.6910, what is your conclusion (answer reject or fail to reject)?

h) Now, provide a conclusion in the context of the problem setting. Make sure to provide an answer and you can skip the part of reject or fail to reject in the answer (answer with one or two short sentences).