exam 2

picture #7

81.32

A sample of final exam scores is normally distributed with a mean equal to 43 and a variance equal to 36. What percentage of scores are between 31 and 55?

95%

A vertical line drawn through a normal distribution at z = -0.60 separates the distribution into two sections, the body and the tail. What proportion of the distribution is in the body?

0.7257

A normal distribution has a mean of µ = 30 with σ = 5. If a vertical line is drawn through the distribution at X = 39, which proportion of the scores are on the left side of the line?

0.9641

Which of the following statement(s) are FALSE? 1.the larger the mean of the population is, the larger the SEM 2.increasing the sample size will decrease standard error 3.the larger the standard deviation in the population, the larger the standard error 4.the larger the sample size and larger the standard deviation in the population, the larger the standard error

1 and 4

picture #

1) 2) 3) 4)

picture #5

1)-.34 2).68 3)-1.03 4)1.37 5)-.68 6)9 7)2.92 8)12.73 9)5.27 10).91

picture #3

1)14 2)20 3)36 4)0 5)2.13

A news poll showed that voters had no preference for either of three candidates. In this example, the probability of a vote for Candidate A equals

1/3

Within a population having standard deviation of σ = 20, the raw score X = 75 has a z-score of 1.75. What is the mean for this population?

40 (with margin: 0)

A sample of final exam scores is normally distributed with a mean equal to 29 and a variance equal to 25. What percentage of scores are between 24 and 34?

68%

picture #4

73.21

picture #6

74.57

What does it mean to say that the sample mean is an unbiased estimator of the population mean?

All options are correct

Which of the following is required to locate proportions of area under the normal curve?

Either I or III

Individuals that score typically to others in a population following a treatment will tend to have extreme z-scores.

False

Which of the following is NOT a characteristic of probability?

Probability is most useful for describing fixed events rather than random events.

All random samples of size n = 9 are selected from a normal population with µ = 55 and σ = 10, and the mean is computed for each sample. Then, all the possible samples of size n = 36 are selected from the same population, and the mean is computed for each sample. Which statement below is true?

The distribution of sample means for samples of n = 36 is less variable than the distribution of sample means for n = 9.

A researcher chooses to collect data from a large sample that represents a population instead of a smaller sample. Which of the following is not a likely consequence of choosing to collect data from a large sample relative to a smaller sample?

The expected value of M will decrease.

A distribution of all sample means or sample variances that could be obtained in samples of a given size from the same population is called

a sampling distribution

picture #1

a) 0 b)0.475 c)0.9426 d)0.2088 e)0.1359

picture #2

a) 0.1587 b)0.9938 c)0.50 d)0.0250

A sampling distribution of the sample mean represents _______

all sample means that could be obtained in samples of a given size from the same population

A normal distribution is normally distributed with a mean of ____ and a variance of ____.

any value; any positive value

Most behavior is believed to ________ a normal distribution.

approximate

Regardless of the distribution of the population, the sampling distribution of sample means will be approximately normally distributed. What theory explains this?

central limit theorem

The mean of the sampling distribution of sample means is

equal to the population mean

A sample of n = 81 scores is obtained from a population with µ = 80 and σ = 27. If the sample mean corresponds to a z-score of +2.33, what is the value of the sample mean?

m=87

A sample is selected from a normal population with µ = 40 and σ = 10. If the sample mean of M = 46 produces a z-score of z = +3.00, then how many scores are in the sample?

n=25

A class consists of 10 male students and 30 female students. If one student is randomly selected from the class, what is the probability of selecting a male student?

p = 10/40

If you made a histogram of a sampling distribution of the sample mean, what values are along the x-axis?

sample means

What is necessary to determine the z-score, given a raw score in a particular set of scores?

the mean and standard deviation for the set

By definition, the probability of an outcome or event is

the ratio of the outcome of interest divided by all possible outcomes

The normal distribution has all of the following characteristics, except that

the total area under the curve is greater than 1.0

All probabilities can be expressed as decimal values ranging from 0.00 to 1.00.

true

The ________ converts any normal distribution with any mean and any variance to a standard normal distribution with a mean of 0 and variance of 1.

z-score (standard normal) transformation

A sample of n = 16 scores has a standard error of σM = 4. What is the standard deviation of the normally distributed population from which the sample was obtained?

σ = 16

A sample of n = 49 scores with M = 43 is selected from a population with µ = 40 and with σ = 21. What is the standard error for the sample mean?

σM = 3