EXAM 3 - JustAnswer



Name__________________

Please highlight or circle the correct answer. Do not remove anything.

1. All possible samples of size n are selected from a population. The mean of each sample

is determined. The mean of the sample means will be:

a. Exactly the same as the population mean. b. larger than the population mean.

c. smaller than the population mean. d. cannot be estimated in advance.

2. If the level of confidence is decreased from 95 percent to 90 percent, but the allowable error and

the standard deviation remain the same, the required sample size for determining the confidence interval will be:

a. increased. b. decreased.

c. unchanged. d. none of the above.

3. When a large number of samples are drawn from a negatively skewed

population, the distribution of the sample means:

a. cannot be predicted in advance. b. will approach a normal distribution.

c. will be positively skewed also. d. none of the above.

4. The Central Limit theorem ensures that the sampling distribution of the sample mean approaches the normal distribution as the sample size increases?

True False

5. We wish to estimate the population proportion. We want to be 95 percent confident of our results and we want the estimate to be with .01 of the population parameter. No estimate of the population proportion is available. What value should we use for p?

a. 1.96 b. 0.01 c. 0.50

| d. We cannot complete the problem, we need more information. |

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|6. The null hypothesis is a claim about |

|a. The size of the sample |

|b. The size of the population |

|c. The value of the sample statistic |

|d. The value of the population parameter |

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|7. The probability of committing a type I error is |

|a. equal to the probability of accepting Ho when Ho is true |

|b. equal to the probability of committing a Type II error |

|c. equal to the probability of accepting H1 when it is false |

|d. equal to the probability of rejecting Ho when Ho is true |

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|8. A company is considering marketing a new local anesthetic. The effective time of the anesthetic |

|that is currently being produced has a normal distribution with an average of 7.4 minutes and a |

|standard deviation of 2 minutes. If the new anesthetic has a mean effective time that is lower, the |

|company will market the new drug. Set up the appropriate test of hypothesis. |

|a. H0: ( ( 7.4 H1: ( >7.4 |

|b. H0: ( ( 7.4 H1: ( < 7.4 |

|c. H0: ( = 7.4 H1: ( [pic]7.4 |

|d. H0: ( < 7.4 H1: ( ( 7.4 |

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|9. Your investment executive claims that the average yearly rate of return on the stocks she recommends is at least 10.0%. You plan to take a |

|sample to test her claim. The correct set of hypotheses is: |

|a. H0: ( < 10.0% H1: ( ( 10.0% |

|b. H0: ( ( 10.0% H1: ( > 10.0% |

|c. H0: ( > 10.0% H1: ( ( 10.0% |

|d. H0: ( ( 10.0% H1: ( < 10.0% |

| |

|10. The manager of a driving school claims that the mean time taken to learn how to drive a car is 8 hours or less for all new drivers. A sample of 16 new |

|drivers showed that the mean time taken by them to learn how to drive the car is 9.5 hours with a standard deviation of 1.5 hours. Test the manager’s claim at |

|the 1% significance level. |

|a. Select the null and alternate hypothesis. |

|1. [pic] 2. [pic] |

|3. [pic] 4. [pic] |

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|b. Determine the critical values of the test statistic. |

|1. [pic] |

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|2. [pic] |

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|3 [pic] |

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|4. [pic] or [pic] |

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|5. [pic] |

|c. Which equation listed below would you use? |

|1. [pic] |

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|2. [pic] |

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|3. [pic] |

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|Using the statistical calculator or manual calculation what is the observed statistic and what is your decision regarding the null hypothesis. |

|Provide a one sentence answer. |

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|Statistic = t = (9.5-8)/(1.5/4) = 4, Then we reject Ho because 4 > 2.60 |

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|11. A department store manager claims that at least 45% of persons who visited this store make a purchase. In a sample of 400 persons who visited the store 150 |

|made a purchase. Test the manager’s claim at the 3% significance level. |

|a. State the null and alternate hypothesis. |

|1. [pic] |

|2. [pic] |

|3. [pic] |

|4. [pic] |

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|b. Determine the rejection region for the decision rule. |

| |

|1. [pic] |

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|2. [pic] |

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|3 [pic] |

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|4. [pic] |

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|c. Which equation listed below would you use? |

|1. [pic] |

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|2. [pic] |

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|3. [pic] |

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|Using the statistical calculator or manual calculation what is the observed statistic and what is your decision regarding the null hypothesis. |

|Provide a one sentence answer. |

| |

|Z = (0.375-0.45)/([0.45(0.55)/400] = -3.015 , since the statistic value -3.015 ................
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