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#### Psyc 233 Exam 2 Online   Part I  Computation

###### Statistics

Psyc 233 Exam 2 Online

Part I  Computation.  An answer by itself with no work may receive no credit!  Try to show as much work as you can for partial credit!

1.  Use the following distribution of sample values to answer the next few questions:

2 4 5 7 9 2 3 9

1A.  Compute the range for the above distribution: (1 point)

1B.  Compute the interquartile range for the above distribution. Show your Work! (2 points)

1C.  Compute the variance for the above distribution.   Show your Work! (3 points)

1D.  Compute the standard deviation for the above distribution (1 point

2.  A researcher measures the heart rate in a population of runners and finds they have an average heart rate of µ = 50, σ = 5.  You do not need to show a graph, only computation work.

2A.  Based on the average heart rate cited above, what proportion would we expect to have a heart rate of 55 or more?  Show your Work! (2 points)

2B.  Based on the average heart rate cited above, what proportion would we expect to have a heart rate of 40 or less?  Show your Work! (2 points)

2C.  Based on the average heart rate cited above, what proportion would we expect to have a heart rate between 55 and 65? Show your Work! (3 points)

2D.  Based on the average heart rate cited above, what heart rate would we expect to cut off the top 10% of the distribution?  Show your Work! (2 points)

3.  A group of toys consists of the following:

5 dolls

7 stuffed animals

3 toy guns

3A.  If I choose at random from the group of toys, what is the probability I get a doll--P(doll)?

3B.  If I choose at random from the group of toys, what is the probability I get a doll or a gun--P(doll or gun)? Show your Work! (2 points)

3C.  If I choose two toys at random (with replacement), what is the probability I get a doll and a stuffed animal—P (doll and stuffed animal)? Show your Work! (2 points)

3D.  If take out toys and give them away as I take them (without replacement), what is the probability I get a doll, a stuffed animal, and a gun—P(doll and stuffed animal and gun)?

4.  Use the following table showing the number of people that meet the following contingencies to answer the next few questions:

Smoke Do not Smoke Total

Get Cancer 10 5 15

Do not get Cancer 5 15 20

Total              15 20 35

4A.  If I pick someone at random from the group what is the probability they have cancer? P(Cancer) Show your Work! (2 points)

4B.  If I pick someone at random from the group what is the probability they do not smoke?  P(Do not Smoke) Show your Work! (2 points)

4C.  If I pick someone at random from the group what is the probability they have cancer and smoke?  P(Cancer and Smoke) Show your Work! (2 points)

4D.  Given that someone smokes, what is the probability they have cancer? P(Cancer | Smoke)

4E.  Given that someone gets lung cancer, what is the probability that that d not smoke?

P(Do not Smoke | Cancer) Show your Work! (2 points)

5.  On a standardized math test:

Males have a mean of  μ = 45 and standard deviation of  σ = 5.

Females have a mean of μ = 50 and standard deviation of σ = 3.

Cindy and Tom also took the same test. Cindy scored 52 while Tom made 50.

Who had the higher score for their gender group?    Show Your Work! (3 points)

Part II Multiple Choice.  Please type the letter of your choice in the blank after the question number.

6.  _____ Which parameters represent a data set with the largest variability?

a.  ? = 5 and ? = 5

b.  ? = 0 and ? = 15

c.  ? = 15 and ? = 0

d.  ? = 2 and ? = 1

7.  _____ Which parameters represent a data set with the largest variability?

a.  ? = 5 and ? = 5

b.  ? = 0 and ? = 15

c.  ? = 15 and ? = 0

d.  ? = 2 and ? = 1

8.  _____Which of the following z-score values represents the location closest to the mean?

a.  z = +0.50

b.  z = +1.00

c.  z = –1.00

d.  z = –2.00

9.  _____What proportion of a normal distribution is located in the tail beyond z = 2.00?

a.  0.9772

b.  0.0228

c.  0.4772

d.  0.0456

10.  Use the following information to answer the next two questions:

Dr. Hill administers a logic test to his students.  The mean for the class is 85.  The standard deviation for the class is 3.5.

10A. _____ What will be the mean for the class if Dr. Hill adds 5 points to everyone’s score?

85

90

95

Cannot be determined

10B.  _____What will be the standard deviation if Dr. Hill adds 5 points to everyone’s score?

a.  3.5

b.  5.5

c.  8.5

d.  Cannot be determined

11.  _____Which of the following is a conditional probability?

a. the probability of being struck by lightning

b. the probability of it raining

c. the probability of having being struck by lightning if it is raining

d. the probability of getting heart disease

12.  _____When the variance is equal to zero...

a.  the standard deviation is equal to 1

b.  the raw scores are negative

c.  all of the raw scores are the same

d.  the variance can never be equal to zero

13.  _____The inter-quartile range is a useful measure of variability…

when the distribution is normal

when there are outliers

when the data is on a nominal scale of measurement

when you have z-scores

14.  _____  If an instructor divides everyone’s score by two, how will the standard deviation change?

a. the new standard deviation and the old standard deviation will be the same

b. the new standard deviation will be twice as large as the old standard deviation

c. the new standard deviation will be half as large as the old standard deviation

d. decrease by 6/3 or, become 2

15.  _____ Whenever the value of the z-score is positive, then

a. the percentile must be greater than the 50th percentile

b. the raw score must be greater than the mean

c. neither a nor b because the z-score is always positive

d. both a and b

16. _____ If X = 30, ( = 35 and ( = 10, then z would be equal to:

a. + 5.0

b. –1.0

c. + .50

d. None of the answers is correct

17._____If an entire population with μ = 60 and σ = 8 is transformed into z-scores, then the distribution of z-scores will have a mean of ___ and a standard deviation of ___.

a.  0 and 1

b.  60 and 1

c.  0 and 8

d.  60 and 8 (unchanged)

End of Exam…………………………………………………………………………

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