Stat 160 Postquiz #7: Over 7.1-7.4



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1. Obtain a 95% confidence interval for the mean if the data are:
       8	9	12	15

(4.8, 17.2)


(7.9, 14.1)
(5.6, 16.4)
(8.3, 13.7)
2. The following is an output from the summary module based on 20 observations (n=20). Obtain a 95% confidence interval for the mean based on the information given.

       x        
 Min.   :581.0
 1st Qu.:598.0   
 Median :606.5   
 Mean   :602.6   
 3rd Qu.:609.0   
 Max.   :614.0   
Rweb:> # STANDARD DEVIATION of x  
Rweb:> var(x)^.5  
[1] 8.94

(585.08, 620.12)


(601.7, 603.5)
(598.7, 606.5)
(0.0,0.95)
3. Suppose that a poll shows that out of 2500 registered voters, 1300 would vote for candidate A. Find a 95% confidence interval for the proportion of the population who would vote for candidate A.

(0, 1)


(.50, .54)
(1300,2500)
(1249.0, 1351.0)
4. The values below are test scores of a random sample of Stat 160 students.

              37    17    23    40    37    39    35    29    32    40    26    39    34
The class bootstrap code obtained the medians of 100 resamples (given below). Find a 95% confidence interval for the median test score of all Stat 160 students.
Sorted Medians
---------------------------

26.0    29.0    29.0    29.0    29.0    29.0    29.0    32.0    32.0    32.0
32.0    32.0    32.0    32.0    32.0    32.0    32.0    32.0    32.0    34.0
34.0    34.0    34.0    34.0    34.0    34.0    34.0    34.0    34.0    34.0
34.0    34.0    34.0    34.0    34.0    34.0    34.0    34.0    34.0    34.0
34.0    35.0    35.0    35.0    35.0    35.0    35.0    35.0    35.0    35.0
35.0    35.0    35.0    35.0    35.0    35.0    35.0    35.0    35.0    35.0
35.0    35.0    35.0    35.0    35.0    35.0    35.0    35.0    37.0    37.0
37.0    37.0    37.0    37.0    37.0    37.0    37.0    37.0    37.0    37.0
37.0    37.0    37.0    37.0    37.0    37.0    37.0    37.0    37.0    37.0
37.0    37.0    37.0    37.0    39.0    39.0    39.0    39.0    39.0    39.0

(29, 39)


(32,39)
(29, 37)
(32, 37)
5. A new drug is being tested in a clinic. Out of the 80 patients who received the drug, 56 were completely cured of their disease. Find a 95% confidence interval for the cure rate of this new drug.

(.517, .883)


(.579, .820)
(.600, .800)
(.547, .853)