# 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)