In: Math
Complete the following problems using R. Name the file with your last name, e.g., “Prob set 6-Smith.eoc”Clearly label problems, and be sure to turn in explanations and interpretations where appropriate.
3.Total cholesterol has been reported to be 200 mg/dL on average in the US by the Centers for Disease Control. You measure total cholesterol on a random sample of 80 Alabama adults, with the intention of comparing Alabamians’ cholesterol level to that of the US average. Data are included in the assignment .xlsx file. Assume
that cholesterol is approximately normally distributed with a known standard deviation of 70 mg/dL.
a.What is the mean value observed for Alabamians’ cholesterol?
b.What is the standard error of Alabamians’ cholesterol assuming the given known standard deviation?
c.Find the 95% confidence interval for the unknown population mean of Alabamians’ cholesterol level values and interpret its meaning.
d.Test the hypothesis that Alabamians have higher average cholesterol than that of the US at the =0.05 level. (Be sure to right down all steps, as in the lecture notes, and interpret the meaning of the test!)
e.How would your answer in (d) change if you used an =0.01 level?
116 |
282 |
213 |
252 |
150 |
219 |
221 |
289 |
226 |
265 |
234 |
256 |
208 |
263 |
155 |
206 |
201 |
283 |
208 |
142 |
279 |
155 |
231 |
143 |
218 |
243 |
162 |
125 |
212 |
149 |
250 |
184 |
210 |
236 |
241 |
294 |
196 |
226 |
184 |
208 |
278 |
144 |
263 |
245 |
212 |
205 |
208 |
151 |
266 |
224 |
276 |
203 |
222 |
199 |
272 |
197 |
176 |
241 |
269 |
217 |
206 |
239 |
238 |
237 |
187 |
203 |
283 |
156 |
283 |
138 |
234 |
198 |
172 |
277 |
172 |
157 |
267 |
160 |
243 |
189 |
From the given data
a) the mean value observed for Alabamians’ cholesterol is 215.53
b.) The standard error of Alabamians’ cholesterol assuming the given known standard deviation is
Sigma / Sqrt(n) = 70 / Sqrt(80) = 7.82623
c.The 95% confidence interval for the unknown population mean of Alabamians’ cholesterol level values and interpret its meaning is
(215.53 - 1.96* 7.82623, 215.53 + 1.96* 7.82623)= (200.1906,230.8694)
d) Test the hypothesis that Alabamians have higher average cholesterol than that of the US at the =0.05 level. (Be sure to right down all steps, as in the lecture notes, and interpret the meaning of the test!)
H0: Alabamians have higher average cholesterol than that of the US is 200 mg/dL o
H1: Alabamians have higher average cholesterol than that of the US is not 200mg/dL o
Test statistic Z = (Xbar - Mu) / Standard error = (215.53 - 200) / 7.82623 = 1.98435
At alpha = 5%, Z critical values = +/- 1.96
Here Z value is not in Z critical values so we reject H0
Thus we conclude that Alabamians have higher average cholesterol than that of the US is not 200mg/dL
e). change if you used an =0.01 level then
Z critical value =+/- 2.58 at alpha = 0.01
Here Z value is in Z critical value so we accept H0
Thus we conclude that Alabamians have higher average cholesterol than that of the US is 200mg/dL
Answer: Change the conclusion