Statistics

If a company wants to prove that the proportion ( p) of its revenues from overseas operations is more than 18%, the null and alternate hypotheses are __________.

H0: p = 0.18 and H1: p ≤ 0.18

H0: p ≤ 0.18 and H1: p > 0.18

H0: p > 0.18 and H1: p < 0.18

H0: p = 0.18 and H1: p > 0.18

The dean of a business school claims that the average starting salary of its graduates is more than 85 (in $000’s). It is known that the population standard deviation is 10 (in $000’s). Sample data on the starting salaries of 64 randomly selected recent graduates yielded a mean of 88 (in $000s). What is the p-value for the hypothesis test to check out the dean’s claim?

0.05

2.40

0.5082

1.65

0.0082

In a two-tailed hypothesis about a population mean with a sample size of 100, σ is known, and alpha = 0.10, the rejection region would be _______.

z < -2.33 and z > 2.33

z > 1.64

z < -1.28 and z > 1.28

z < -1.64 and z > 1.64

z > 1.28

A researcher is testing a hypothesis of a single mean. The critical z value for = .05 and a one-tailed test is 1.645. The observed z value from sample data is 1.13. The decision made by the researcher based on this information is to ______ the null hypothesis.

restate the null hypothesis

reject

fail to reject

redefine

change the alternate hypothesis into

A researcher is testing a hypothesis of a single mean. The critical z value for = .05 and a two-tailed test is +1.96. The observed z value from sample data is -2.11. The decision made by the researcher based on this information is to _____ the null hypothesis.

change the alternate hypothesis into

redefine

fail to reject

reject

restate the null hypothesis

In performing a hypothesis test where the null hypothesis is that the population mean is 4.8 against the alternative hypothesis that the population mean is not equal to 4.8, a random sample of 25 items is selected. The sample mean is 4.1 and the sample standard deviation is 1.4. It can be assumed that the population is normally distributed. The level of significance is selected to be 0.10. The table " t" value for this problem is _______.

2.797

3.227

1.711

2.492

1.318

The local oil changing business is very busy on Saturday mornings and is considering expanding. A national study of similar businesses reported the mean number of customers waiting to have their oil changed on Saturday morning is 3.6. Suppose the local oil changing business owner, wants to perform a hypothesis test. The null hypothesis is the population mean is 3.6 and the alternative hypothesis that the population mean is not equal to 3.6. The owner takes a random sample of 16 Saturday mornings during the past year and determines the sample mean is 4.2 and the sample standard deviation is 1.4. It can be assumed that the population is normally distributed. The observed " t" value for this problem is _______.

1.33

0.43

1.71

0.71

0.05

The weight of a USB flash drive is 30 grams and is normally distributed. Periodically, quality control inspectors at Dallas Flash Drives randomly select a sample of 17 USB flash drives. If the mean weight of the USB flash drives is too heavy or too light the machinery is shut down for adjustment; otherwise, the production process continues. The last sample showed a mean and standard deviation of 31.9 and 1.8 grams, respectively. Using α = 0.10, the appropriate decision is _______.

do nothing

reject the null hypothesis and shut down the process

reject the null hypothesis and do not shut down the process

fail to reject the null hypothesis and do not shut down the process

fail to reject the null hypothesis and shut down the process

The weight of a USB flash drive is 30 grams and is normally distributed. Periodically, quality control inspectors at Dallas Flash Drives randomly select a sample of 17 USB flash drives. If the mean weight of the USB flash drives is too heavy or too light the machinery is shut down for adjustment; otherwise, the production process continues. The last sample showed a mean and standard deviation of 31.9 and 1.8 grams, respectively. Using α = 0.10, the critical " t" values are _______.

-2.567 and 2.567

-2.131 and 2.131

-2.120 and 2.120

-1.753 and 1.753

-1.746 and 1.746

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