The cholesterol level of patients who had heart attacks was measured two days after the heart attack and then again four days after the heart attack.The researchers want to see if the cholesterol level of patients who have heart attacks reduces as the time since their heart attack increases.Data is in following table:

Patient Cholesterol day 2 Cholesterol day 4

1 270 218

2 236 234

3 210 214

4 142 116

5 280 200

6 272 276

7 160 146

8 220 182

9 226 238

10 242 288

11 186 190

12 266 236

13 206 244

14 318 258

15 294 240

16 282 294

17 234 220

18 224 200

19 276 220

20 282 186

21 360 352

22 310 202

23 280 218

24 278 248

25 288 278

26 288 248

27 244 270

28 236 242

Determinesamplemeanofdifferencesxd(to the nearest ten-thousandth)

Determine sample standard deviation of differencessd(to the nearest ten-thousandth)

Enter the level of significance x used for this test:

Determine degrees of freedom for the sample of differences df_d

determine t - score associated with critical value: t_c (to the nearest ten-thousandth)

Determine "error boud of the mean of difference" E (to the nearest ten-thousandth)

Determine confidence interval of the mean difference u_d (enter lower and upper bound to the nearest ten-thousandth)

Using the confidence interval, select the correct description of the result of the survey:

a. we estimate with 98% confidence that the true population mean difference in cholesterol level of patients who had heart attacks two days and four days after the heart attack is between 5.40mg/dL and 41.17 mgdL.

b. we estimate with 98% confidence that the true proportional difference in cholesterol level of patients who had heart attacks two days and four days after the heart attack is between 5.40mg/dL and 41.17 mgdL.

c. we estimate with 98% confidence that the true population mean cholesterol level of patients who had heart attacks two days and four days after the heart attack is between 5.40mg/dL and 41.17 mgdL.

d. we estimate with 98% confidence that the true sample mean cholesterol level of patients who had heart attacks two days and four days after the heart attack is between 5.40mg/dL and 41.17 mgdL.