so234 ch 5

The probability that a randomly selected case will have a score beyond ± 1.00 standard deviation of the mean is... a. 0.6826. b. 0.5000. c. 0.3174. d. 1/2 of the area of 1 standard deviation.

a. 0.6826.

The Z score table gives the area between a score and the mean. For a Z score of -1.00, that area (in percentages) is... a. 34.13% b. -34.13% c. 68.26% d. -68.26%

a. 34.13%

The area between the mean and a Z score of +1.50 is 43.32%. This score is higher than BLANK of the scores in the distribution. a. 43.32% b. 51.50% c. 57.68% d. 93.32%

a. 43.32%

The mean score on a final chemistry exam was 75, and the standard deviation of the scores was 5. If the distribution is normal and your score was 70, what percentage of the scores was lower than yours? a. 15.87% b. 30.00% c. 34.13% d. 50.00%

a. 15.87%

The mean on a standardized test is 100 and the standard deviation is 35. Your score is 65. What percentage of the scores were higher than yours? a. About 84% b. No more than 50% c. About 34% d. About 16%

a. About 84%

The standardized normal distribution (or Z distribution) has... a. a mean of 0 and a standard deviation of 1. b. a mean of 1 and a standard deviation of 0. c. a mean equal to the average of the scores and a standard deviation equal to the mean. d. a mean of 1 and a standard deviation of 1.

a. a mean of 0 and a standard deviation of 1.

The Z scores of two test scores are - 1.17 and + 2.38. To find the total area between these two scores... a. add the column b areas together. b. subtract each score from the mean and divide the result by the standard deviation. c. add the column b area to the column c area. d. add the column c areas.

a. add the column b areas together.

As the standard deviation of a normal distribution increases, the percentage of the area between ± 1 standard deviation will... a. increase. b. stay the same. c. decrease. d. become non-symmetrical.

a. increase.

A Z score of +1.00 indicates a score that lies... a. one standard deviation unit to the right of the mean. b. one standard deviation unit to the left of the mean. c. 1/2 of one standard deviation unit on each side of the mean. d. Any of the above are possible.

a. one standard deviation unit to the right of the mean.

By definition, the normal curve is... a. symmetrical. b. positively skewed. c. negatively skewed. d. empirical.

a. symmetrical.

Distributions of IQ scores are normally distributed because... a. the underlying quality being tested - intelligence - is normally distributed. b. IQ tests are designed to produce in normal distributions. c. there is no cultural bias in the tests. d. they reflect the natural distribution of intelligence: human beings are genetically programmed to have an average intelligence of about 100.

a. the underlying quality being tested - intelligence - is normally distributed.

A defining characteristic of the normal curve is that it is... a. theoretical. b. positively skewed. c. negatively skewed. d. perfectly nonsymmetrical.

a. theoretical.

To find the area above a positive Z score or below a negative Z score you would... a. subtract the value of the Z score from the mean. b. use the "Area Beyond Z" column of the Z score table. c. add the value of the Z score to the area beyond the mean. d. add the area between the Z score and the mean to 100%.

b. use the "Area Beyond Z" column of the Z score table.

The average homicide rate for the cities and towns in a state is 10 per 100,000 population with a standard deviation of 2. If the variable is normally distributed, what is the probability that a randomly selected town will have a homicide rate greater than 14? a. 0.34 b. 0.68 c. 0.50 d. 0.02

d. 0.02

A social researcher has constructed a measure of racial prejudice and obtained a distribution of scores on this measure from a randomly selected sample of public office holders. The scores were normally distributed with a mean of 45 and a standard deviation of 7. What is the probability that a randomly selected case from the sample will have a score less than 38? a. 0.4526 b. 0.5018 c. 0.5200 d. 0.1587

d. 0.1587

If a Z score is + 1.00, then the value of the corresponding raw score would be... a. 0. b. the same as the mean of the empirical distribution. c. equal to the mean of the empirical distribution plus one standard deviation. d. probably a negative number.

b. the same as the mean of the empirical distribution.

If a Z score is 0, then the value of the corresponding raw score would be... a. 0. b. the same as the mean of the empirical distribution. c. the same as the standard deviation of the empirical distribution. d. probably a negative number.

b. the same as the mean of the empirical distribution.

What is the probability that a randomly selected case from the sample in the previous question would have a score of 52 or more? a. 0.7500 b. 0.6826 c. 0.3413 d. 0.1587

d. 0.1587

In a distribution of 150 test scores, the mean grade was an 82 and the standard deviation was 8. If a student scored a 93, what would their equivalent Z score be? a. 1.13 b. 1.38 c. 0.68 d. 1.38

d. 1.38

When an empirical normal distribution of scores is standardized... a. the mean will become 0. b. the standard deviation will become 1. c. each score will be converted to a Z score. d. All of the above.

d. All of the above.

To obtain the area below a positive Z score or above a negative Z score you would... a. subtract the value of the Z score from the mean. b. subtract the area in the "Area Beyond Z" column of the Z score table from 50%. c. add the value of the Z score to the area beyond the mean. d. add the area between the Z score and the mean to 50%.

d. add the area between the Z score and the mean to 50%.

The area between a negative Z score and a positive Z score can be found by... a. subtracting the Z scores from each other. b. subtracting each Z score from the mean and adding the results. c. adding the Z scores and finding the area in the Z score table for the summed Z scores. d. adding the areas between each Z score and the mean.

d. adding the areas between each Z score and the mean.

If a case has a Z score of 2.3, the standard deviation would be... a. 4.6 b. 1 c. 0 d. cannot calculate based on this information.

d. cannot calculate based on this information.

In the normal curve, the mean is... a. greater than the median. b. greater than the mode. c. less than the median. d. equal to the median and mode.

d. equal to the median and mode.

Unlike empirical distribution, the theoretical normal curve is... a. positively skewed. b. negatively skewed. c. bimodal. d. perfectly symmetrical.

d. perfectly symmetrical.

To estimate probabilities, set up a fraction with the number of BLANK in the numerator and the number of BLANK in the denominator. a. successes, failures b. possible outcomes, successes c. failures, successes d. successes, possible outcomes

d. successes, possible outcomes

The area between the mean and a Z score of +1.50 is 43.32%. This score is less than BLANK of the scores in the distribution. a. 43.32% b. 6.68% c. 3.32% d. 93.32%

b. 6.68%

Assuming a normal distribution of 1000 cases, how many cases will be farther away from the mean than + 3 standard deviations? a. At least 500 b. About 3 c. 327 d. It is impossible to estimate

b. About 3

On all normal curves the area between the mean and +1 standard deviation will be... a. about 34% of the total area. b. about 68% of the total area. c. about 95% of the total area. d. about 99% of the total area.

b. about 68% of the total area.

On all normal curves the area between the mean and ± 1 standard deviation will be... a. about 34% of the total area. b. about 68% of the total area. c. 50% of the total area. d. 99.9% of the total area.

b. about 68% of the total area.

On all normal curves the area between the mean and ± 2 standard deviations will be... a. about 34% of the total area. b. about 95% of the total area. c. less than 50% of the total area. d. about 68% of the total area.

b. about 95% of the total area.

Column c in the normal curve table lists "areas beyond Z". This is the area... a. below a positive Z score. b. above a negative Z score. c. between two positive Z scores. d. above a positive Z score.

b. above a negative Z score.

A common real world application of the normal curve is... a. measuring income levels. b. assigning exam grades. c. setting government budgets. d. None of the above.

b. assigning exam grades.

The text discusses an application of probability theory that involved... a. betting on horse races. b. casino gambling. c. cheating on final exams. d. betting on the outcome of the presidential election.

b. casino gambling.

If a case is randomly selected from a normal distribution, the score of the case will most likely be... a. equal to the mean in value. b. close to the mean in value. c. at least 1 standard deviation above the mean. d. at least 1 standard deviation below the mean.

b. close to the mean in value.

The Z scores of two tests scores are + 1.2 and + 1.5. To obtain the area between these scores... a. subtract the Z scores and find the area of the difference in the Z score table. b. find the area between each score and the mean in the Z score table and then subtract the smaller area from the larger area. c. find the area between each score and the mean in the Z score table and then subtract the difference between them from 100%. d. find the area beyond each score in the Z score table and subtract the difference between the areas from the mean.

b. find the area between each score and the mean in the Z score table and then subtract the smaller area from the larger area.

In terms of construction, the normal curve is what kind of chart? a. pie chart. b. line chart. c. histogram. d. bar chart.

b. line chart.

Converting scores into Z scores standardizes the original distribution to units of the... a. median. b. standard deviation. c. mean. d. percentage.

b. standard deviation.

A Z score of -2.00 indicates a score that lies... a. two standard deviation units to the right of the mean. b. two standard deviation units to the left of the mean. c. 0.5 of one standard deviation unit on each side of the mean. d. Any of the above are possible, depending on the value of the mean.

b. two standard deviation units to the left of the mean.

What is the probability that a randomly selected case from a normally distributed distribution will have a score between -1.00 and the mean? a. 0.34 b. 0.16 c. 0.50 d. 0.86

c. 0.50

The average homicide rate for the cities and towns in a state is 10 per 100,000 population with a standard deviation of 2. If the variable is normally distributed, what is the probability that a randomly selected town will have a homicide rate greater than 8? a. 0.34 b. 0.68 c. 0.84 d. 0.01

c. 0.84

The probability of getting a 1 in a single toss of a six sided die would be... a. 2 to 1. b. 60 to 1. c. 1 in 6. d. impossible to estimate with the information given.

c. 1 in 6.

The area beyond ± 2 standard deviations contains approximately what % of the area under the normal curve? a. 75% b. 50% c. 99% d. 5%

c. 99%

Assuming a normal distribution of 1000 cases, how many cases will be within ± 1 standard deviations of the mean? a. At least 500 b. About 3 c. About 680 d. It is impossible to estimate

c. About 680

The area between two negative Z scores can be found by... a. adding the Z scores and finding the area below the total Z score. b. subtracting the Z scores and finding the total area above the total Z score. c. finding the area between each Z score and the mean and subtracting the smaller area from the larger. d. finding the area between each Z score and the mean and adding the areas.

c. finding the area between each Z score and the mean and subtracting the smaller area from the larger.

The tails of the theoretical normal curve... a. intersect with the horizontal axis between the 4th and 5th standard deviation. b. intersect with the horizontal axis beyond the 5th standard deviation. c. never touch the horizontal axis. d. maintain the same distance above the horizontal axis beyond the 3rd standard deviation.

c. never touch the horizontal axis.

As used in the social sciences, probabilities are a type of BLANK which can vary from BLANK. a. percentage, 0 to 1 b. fraction, 0 to 100 c. proportion, 0.00 to 1.00 d. Z score, 0 to infinity

c. proportion, 0.00 to 1.00