APS: Unit 5/6 Quiz- Inference

The proportion of orange salamanders along a certain stream is known to be 10%. Use a normal model to approximate the probability that, for a sample of 100 salamanders along this stream, at least 20 are orange.

• 0.0004

• 0.1937

• 0.3707

• 0.6293

• 0.9996

At a man-made lake in central Pennsylvania, an average of 50 gallons of water flow over the spillway every minute, with a standard deviation of 15 gallons. If the distribution of the number of gallons that flow over the spillway is assumed to be approximately normal, what is the probability that, for any randomly chosen minute, fewer than 20 gallons of water will flow over the spillway?

• 0.0228

• 0.0456

• 0.0968

• 0.1936

• 0.9772

With an α-level of 5%, what is the power of a test against an alternative for which the probability of a Type II error is 3%?

• 3%

• 5%

• 95%

• 97%

• The power cannot be determined from the given information.

A major university expresses 95% confidence that about 90% to 93% of its students find employment in their field within one year of graduation What is the margin of error implied in this statement?

• 1%

• 1.5%

• 3%

• 5%

• 6%

Owners of a chain of ice cream shops recently examined sales figures and noticed that on a randomly selected day, 21 of 103 ice cream customers from their shop located in the eastern part of the state ordered soft-serve ice cream, while 29 of 132 ice cream customers from their shop located in the western part of the state ordered soft-serve ice cream. Is there a significant difference in the proportions of customers who favor soft-sere ice cream in the eastern and western parts of the state?

• There is a significant difference at the 0.001 level.

• There is a significant difference at the 0.10 level but not at the 0.05 level.

• There is a significant difference at the 0.05 level but not at the 0.01 level.

• There is a significant difference at the 0.01 level but not at the 0.001 level.

• There is no significant difference at the 0.10 level.

A survey is to be conducted to determine the proportion of U.S. voters who support additional aid to African nations to fight poverty and HIV/AIDS. Of the proposed sample sizes, which is the smallest that will guarantee a margin of error of no more than 4% for a 90% confidence level?

• 225

• 325

• 425

• 525

• 625

A sample of 45 Turkey De-Lite hot dogs yielded a mean sodium content of 290 mg with a standard deviation of 28 mg. Construct a 98% confidence interval for the average sodium content in Turkey De-Lite hot dogs.

• 290 ± 1.96 (4.174)

• 290 ± 2.02 (4.174)

• 290 ± 2.33 (4.174)

• 290 ± 2.41 (4.174)

• 290 ± 2.69 (4.174)

An analyst is comparing data collected from randomly assigned test subjects who used two different types of hand cream (designated I and II), each for a period of six months. The subjects used one type of cream on one hand and the second on the other and reported a "softness" factor on a scale of 1 to 10 for each hand. What steps should the analyst take to determine which cream is more effective?

• Calculate the mean difference between the right-hand results and the left-hand results, then carry out a one-sample z-test.

• Calculate the difference in means between the right-hand results and the left-hand results, then carry out a two-sample z-test.

• Calculate the mean difference between the right-hand results and the left-hand results, then carry out a one-sample t-test.

• Calculate the difference in means between the right-hand results and the left-hand results, then carry out a two-sample t-test.

• Calculate the individual differences between the Type I and Type II results for each subject, then carry out a one-sample t-test for the mean difference.

A 95% confidence interval for the population mean is (98.52, 101.48). What is the 90% confidence interval constructed from the same data?

• (98.02, 101.98)

• (98.22, 101.78)

• (98.35, 101.65)

• (98.44, 101.55)

• (98.76, 101.23)

A random sample of 100 married couples, in which both partners are currently employed, is obtained. State the hypotheses to test whether, on average, men take more sick days than women.

• H_o: μ _w-m = 0; H_a = μ _w-m > 0

• H_o: μ _w-m = 0; H_a = μ _w-m < 0

• H_o: μ_w - μ_m = 0; H_a = μ_w - μ_m > 0

• H_o: μ_w - μ_m = 0; H_a = μ_w - μ_m < 0

• H_o: μ_w - μ_m = 0; H_a = μ_w - μ_m ≠ 0