INTRODUCTION: For questions #1 through #4 Suppose that you are a health research

Question

INTRODUCTION: For questions #1 through #4 Suppose that you are a health researcher for the Cleveland Clinic. You know that, across the entire country, the average weight of a baby born is 7.50 pounds with a known population standard deviation of 1.25 pounds. However, you have been reading reports from doctors at Cleveland Clinic's Marymount Hospital expressing concern over low birth weights at their facility as of late. You decide to investigate. Looking at the last 50 babies born at the hospital, you find that the average birth weight is 6.96 pounds. Assuming a one-sided test, what is the alternative hypothesis if you are trying to determine if babies delivered at Marymount Hospital suffer from low birth weight (where mu represents the population mean)? H1: mu 7.50 H1: mu

Explanation / Answer

1) The alternative hypothesis tends to establish the proposition that babies born suffer from low birth weight that is weight lessesr than population mean weight of babies across the country. Thus, suitable alternative hypothesis is

H0:mu<7.50

The first option is opposite of what the reseracher wants to establish, and middle two options are not correct as they use sample mean to denote alternative hypothesis.

2) Z=(xbar-mu)/(sigma/sqrt N), where, xbar is sample mean, mu is population mean, sigma is population standard deviation and N is sample size.

=(6.96-7.50)/(1.25/sqrt 50)

=-3.05

3) from information given, 1-alpha=0.99, therefore, alpha=0.01, and for left tailed test, the critical Z is -2.33.

4) Per rejection rule based on critical value, reject null hypothesis if observed z>=critical z. Here, -3.05>-2.33. Therefore, reject H0.

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