Midterm Soc./Psyc 270-80

For a population with a standard deviation of σ = 10, what is the z-score corresponding to a score that is 5 points below the mean?

-0.50

What z-score value separates the highest 70% of the scores in a normal distribution from the lowest 30%?

-0.52

For any distribution, what is the z-score corresponding to the mean?

0

IQ scores form a normal distribution with μ = 100 and σ = 15. Individuals with IQs above 140 are classified in the genius category. What proportion of the population consists of geniuses?

0.0038

A vertical line is drawn through a normal distribution at z = 0.80. What proportion of the distribution is on the right-hand side of the line?

0.2119

A sample of n = 9 individuals is selected from a population with μ = 60 and σ = 6, and a treatment is administered to the sample. After treatment, the sample mean is M = 63. What is the value of Cohen's d for this sample?

0.50

A sample of n = 4 scores is selected from a normal population with a mean of μ = 50 and a standard deviation of σ = 20. What is the probability of obtaining a sample mean greater than M = 48?

0.5793

A random sample of n = 9 scores is selected from a normal distribution with μ = 80 and σ = 12.What is the probability that the sample mean will be between 76 and 84?

0.6826

For a population with μ = 60, which of the following values for the population standard deviation would cause X = 68 to have the most extreme position in the distribution?

1

A sample of n = 4 scores is selected from a population with μ = 50 and σ = 12. If the sample mean is M = 56, what is the z-score for this sample mean?

1.00

What is the variance for the following population of scores? Scores: 5, 2, 5, 4

1.5

On an exam with a mean of μ = 70, you have a score of X = 65. Which of the following values for the standard deviation would give you the highest position within the class?

10

A sample consists of n = 16 scores. How many of the scores are used to calculate the range?

2

For a population with a standard deviation of σ = 6, what is the z-score corresponding to a score that is 12 points above the mean?

2

What is the median for the set of scores shown in the frequency distribution table? X f 1 4 2 3 3 2 4 1 5 1

2

A sample of n = 100 scores is selected from a population with μ = 80 with σ = 20. On average, how much error is expected between the sample mean and the population mean?

2 points

A random sample of n = 4 scores is obtained from a population with a mean of μ = 80 and a standard deviation of σ = 10. If the sample mean is M = 90, what is the z-score for the sample mean?

2.00

What is the median for the population of scores shown in the frequency distribution table? X f 1 2 2 4 3 3 4 2 5 1

2.5

A sample of n = 16 scores is selected from a population with μ = 80 with σ = 20. On average, how much error would be expected between the sample mean and the population mean?

20 points

What is the value of ∑ X 2 for the scores 1, 0, 2, 4?

21

A sample of n = 4 scores has ∑X = 8 and ∑ X 2 = 40. What is the value of SS for this sample?

24

A sample is selected from a population with μ = 50 and σ = 12. If the sample mean of M = 56 produces a z-score of z = +1.00, then how many scores are in the sample?

4

A sample has a mean of M = 90. If each score in the sample is multiplied by 5, then what is the mean for the new distribution?

450

For a sample with M = 50 and s = 12, what is the X value corresponding to z = -0.25?

47

What is the median for the following set of scores? Scores: 1, 2, 6, 11, 17

6

If random samples, each with n = 9 scores, are selected from a normal population with μ = 80 and σ= 18, how much difference, on average, should there be between a sample mean and the population mean?

6 points

For a population with μ = 80 and σ = 10, what is the X value corresponding to z = -2.00?

60

A sample of n = 4 scores is obtained from a population with μ = 70 and σ = 8. If the sample mean corresponds to a z-score of 2.00, what is the value of the sample mean?

78

What is the effect of decreasing the alpha level (for example, from α = .05 to α = .01)?

All of the other options are results of decreasing alpha.

For the following frequency distribution of exam scores, what is the lowest score on the exam? x f 90-94 3 85-89 4 80-84 5 75-79 2 70-74 1

Cannot be determined

For the following frequency distribution, what is ∑ X? X f 60-64 5 55-59 11 50-54 8 45-49 9 40-44 6

Cannot be determined

A sample has a mean of M = 40. If 10 points are added to one of the scores, what is the new value for the sample mean?

Cannot be determined from the information given

Which of the following accurately describes the effect of increasing the sample size?

Decreases the standard error and has no effect on the risk of a Type I error

What happens to the expected value of M as sample size increases?

It stays constant

For a sample of n = 30 scores, X = 45 corresponds to z = 1.50 and X = 40 corresponds to z = +1.00.What are the values for the sample mean and standard deviation?

M=30 and s=10

For a sample of n = 100 scores, X = 45 corresponds to z = 0.50 and X = 52 corresponds to z = +1.00.What are the values for the sample mean and standard deviation?

M=31 and s=7

Last week Tim got a score of X = 54 on a math exam with μ = 60 and σ = 8. He also got X = 49 on an English exam with μ = 55 and σ = 3, and he got X = 31 on a psychology exam with μ = 37 and σ= 4. For which class should Tim expect the best grade?

Math

A population with a mean of μ = 6 has ∑ X = 54. How many scores are in the population?

N=9

Students are asked about their type of transportation to school (e.g. bus, walk, car). What scale of measurement is being used for this variable?

Nominal

What kind of measurement scale is necessary to conclude that one score is twice a big as another?

Ratio

If a hypothesis test produces a z-score in the critical region, what decision should be made?

Reject the null hypothesis

A hypothesis test involves a comparison of which two elements?

Research results from a sample and a hypothesis about a population

A researcher administers a treatment to a sample of participants selected from a population with μ = 80. If the researcher obtains a sample mean of M = 88, which combination of factors is most likely to result in rejecting the null hypothesis?

Standard deviation = 5 and n=50

Which of the following is a consequence of increasing variability?

The distance from one score to another tends to increase, and a single score tends to provide a less accurate representation of the entire distribution.

A random sample of n = 60 scores is selected from a population. Which of the following distributions definitely will be normal?

The distribution of sample means will form a normal distribution.

What is the preferred measure of central tendency for scores measured on an ordinal scale?

The median

What kind of frequency distribution graph shows the frequencies as bars that are separated by spaces?

a bar graph

If a distribution of scores is shown in a bar graph, you know that the scores were measured on a(n) _________ scale of measurement.

nominal or ordinal

A researcher is curious about the average monthly cell phone bill for high school students in the state of Florida. If this average could be obtained, it would be an example of a ______.

parameter

A researcher uses an anonymous survey to investigate the television-viewing habits of American adolescents. Based on the set of 356 surveys that were completed and returned, the researcher finds that these students spend an average of 3.1 hours each day watching television. For this study, the set of 356 students who returned surveys is an example of a _______.

sample