Question

SECTION2- Sampling Distributions

6. The amount of time that you have to wait before seeing the doctor in the doctor's office is normally distributed with a mean of 15.2 minutes and a standard deviation of 15.2 minutes. If you take a random sample of 35 patients, what is the probability that the average wait time is greater than 20 minutes? (Hint: Round the probability value to 2 decimal places.) Show your calculations.

• A. 0.16
• B. 0.09
• C. 0.03
• D. 0.28

7. A basketball player shoots 60 free throws a day and historically makes 75 percent of them. What is the probability that he will make at most 80 percent tomorrow? Show your calculations.

• A. 0.1056
• B. 0.1867
• C. 0.8944
• D. 0.8133

8. If a sample of size 100 is taken from a population whose standard deviation is equal to 100, then the standard error of the mean is equal to: Show your calculations.

• A. 10
• B. 10,000
• C. 100
• D. 1,000

SECTION 3 - Confidence 1

9. The following sample was taken from a normally distributed population: 20, 27, 15, 20, 16, 22, and 13. A 95% confidence interval for the population mean using this sample is: Show your calculations.

• A. 19 ± 4.402
• B. 19 ± 5.603
• C. 19 ± 2.201
• D. 19 ± 8.804

10. In a recent survey of 600 adults, 16.4% indicated that they had fallen asleep in front of the television in the past month. Which of the following intervals represents a 98% confidence interval for the population proportion? Show your calculations.

• A. 0.137 to 0.192
• B. 0.140 to 0.189
• C. 0.129 to 0.199
• D. 0.143 to 0.186

Answer 1

P(z<Z) table :

section 2:

6.

SD of sample = SD / (n^0.5)

= 15.2 / 35^0.5

= 2.57

ANSWER : C. 0.03

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