Deck 5: Probability and the Normal Curve

Question 1

Roughly __________ of the total area under the normal curve rests between two standard Deviations above and below the mean.

A)68%
B)47%
C)99%
D)95 %

Answer 1

95 %

Question 2

A probability distribution is essentially a frequency distribution of percentages for:

A)no cases.
B)10 cases.
C)a small number of cases.
D)an infinite number of cases.

Answer 2

an infinite number of cases.

Question 3

In a symmetrical distribution, what percent of the scores fall above the mean?

A)34%
B)68%
C)95%
D)50 %

Answer 3

50 %

Question 4

If the probability (p) of giving birth to a boy is .51, and a woman can only give birth to a Single boy or girl, then the probability of giving birth to a girl is:

A).94
B)1 - p
C).49
D)b and c

Question 5

The probability of a student correctly guessing the answer to this question is:

A).20.
B).25.
C).50.
D).3 0.

Question 6

The probability of flipping 2 heads in 2 flips of the same coin is:

A).50.
B).75.
C).25.
D).5 2.

Question 7

Which of the following is true of the normal distribution?

A)The normal curve is symmetrical.
B)The normal curve is unimodal.
C)The tails extend indefinitely in either direction.
D)All of the above are true.

Question 8

Roughly __________ of the total area under the normal curve rests between the mean and One standard deviation above the mean.

A)50%
B)40%
C)34%
D)17 %

Question 9

The question below refers to the following situation:
The average price for a new car is $18,000 and the standard deviation is $1,500. Calculate The z scores for the following individual score:
If X = 19,000, z = __________.

A)2.5
B)-0.67
C)11.33
D)0.67

Question 10

A normal curve:

A)is a theoretical ideal or model.
B)can be used to describe distributions.
C)is used in statistical decision making.
D)All of the above are true of the normal curve.

Question 11

Empirical probability distributions are those dependent on:

A)observation to determine or estimate their values.
B)mathematics alone to determine or estimate their values.
C)calculus to determine or estimate their values.
D)computers alone to determine or estimate their values.

Question 12

If 68% of IQ scores are between 85 and 115, what is the probability of meeting a person in The population within that IQ range?

A).068
B)6.8
C).68
D).9 5

Question 13

The question below refers to the following situation:
The average price for a new car is $18,000 and the standard deviation is $1,500. Calculate The z scores for the following individual score:
If X = 21,000, z = __________.

A)2.00
B)1.19
C)-1.33
D)-1 .85

Question 14

A probability distribution has:

A)no mean.
B)no standard deviation.
C)a mean and a standard deviation.
D)none of the above.

Question 15

The probability of rolling a '4' on one toss of a standard six-sided die is:

A).1
B).167
C)1.67
D).2 5

Question 16

The normal curve is:

A)a theoretical ideal.
B)applicable to all real life research situations.
C)positively skewed.
D)all of the above.

Question 17

Which of the following is NOT true of the normal curve?

A)It is skewed.
B)It is a probability distribution.
C)Its total area contains 100% of cases.
D)The mode, median, and mean are identical.

Question 18

The question below refers to the following situation:
The average price for a new car is $18,000 and the standard deviation is $1,500. Calculate The z scores for the following individual score:
If X = 16,000, z = __________.

A)9.33
B)-1.33
C).78
D).9 9

Question 19

Probability is defined as:

A)
B)
C)
D)

Question 20

Which of the following is true of probabilities?

A)A probability varies from 0 to 1.0.
B)A 0 probability implies something is possible.
C)A 1.0 probability implies something is impossible.
D)None of the above are true.

Question 21

Which of the following is NOT true of the normal curve?

A)It can be applied to any distribution encountered by a researcher.
B)It helps with interpretation of the standard deviation.
C)It can be used to describe distributions of scores.
D )It can be used to make statements about probabilities.

Question 22

The symbol for the standard deviation of a probability distribution is __________.

Question 23

The question below refers to the following table:
The percent of TOTAL cases that have a z score less than or equal to 1.46 is __________

Question 24

The distribution of test scores for the population is normal, with a mean of 33 and a standard deviation of 6.3.
The percentage of the population which scored below John is __________.

Question 25

The question below refers to the following table:
The percent of area beyond z = 1.44 is __________.

Question 26

The distribution of test scores for the population is normal, with a mean of 33 and a standard deviation of 6.3.
The percentage of the population which scored above Kim is __________.

Question 27

The question below refers to the following table:
The probability of obtaining a score between z = -1.40 and the mean is __________.

Question 28

Fifty percent of the scores fall below the mean in a normal curve.

Question 29

A z-score tells nothing about the distance of a score from the mean.

Question 30

One hundred percent of the scores fall under the area of the normal curve.

Question 31

The question below refers to the following table:
The percent of area between the mean and z = 1.45 is __________.

Question 32

Assume citizens were asked about their views on healthcare reform. The results are listed
below.
What is the probability of selecting at random from this group a Democrat who supports healthcare reform?

Question 33

Assume citizens were asked about their views on healthcare reform. The results are listed
below.
What is the probability of selecting at random from this group a citizen who is a Democrat?

Question 34

The question below refers to the following table:
The percent of area between the z = 1.40 and z = 1.49 is __________.

Question 35

A number with a z-score of zero is equal to the mean.

Question 36

A z-score is a specific case's distance from the mean in __________ units.

Question 37

The symbol for the mean of a probability distribution is __________.

Question 38

A z-score does NOT allow comparison of different scores from different distributions.

Question 39

The distribution of test scores for the population is normal, with a mean of 33 and a standard deviation of 6.3.
The percentage of the population that scored between Kim and John is __________.

Question 40

Normal curves are often used to compare samples to populations.

Question 41

Assume citizens were asked about their views on healthcare reform. The results are listed below.
What is the probability of selecting at random from this group a citizen who does NOT support healthcare reform?

Question 42

Assume citizens were asked about their views on healthcare reform. The results are listed below.
What is the probability of selecting at random from this group a citizen who does support healthcare reform?

Question 43

Assume citizens were asked about their views on healthcare reform. The results are listed below.
What is the probability of selecting at random from this group a Republican who does NOT support healthcare reform?