STP 420 Test 2
NAME:______ASU ID: ______
STP 420 SUMMER 2001
Exam 2
There are 7 questions on this test adding up to a total of 105 points. Read all the questions carefully.
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Signature: ______
Date: ______
Directions: Please read the questions carefully and place your answer in the space
provided at the end of each question. Show all necessary working.
1.Firearms are second to motor vehicles as a cause of non disease deaths in the United States. Here are counts from a study of all firearm-related deaths in Milwaukee, Wisconsin, between 1990 and 1994. (Data from S. W. Hargarten et al., “Characteristics of firearms involved in fatalities,” Journal of American Medical Association, 275 (1996), pp. 42-45.) We want to compare the types of firearms used in homicides and in suicides. We suspect that long guns (shotguns and rifles) will more often be used in suicides because many people keep them at home for hunting.
Death byFirearms / Homicides / Suicides
Handgun / 468 / 124
Shotgun / 28 / 22
Rifle / 15 / 24
Not specified / 13 / 5
Total / 524 / 175
a.[5]Determine the percentage of deaths caused by handguns.
b.[5]Present the marginal distribution of firearms in a table form.
c.[5]Present the conditional distribution of firearms for the suicide deaths.
d.[5]Determine the percentage of deaths caused by suicides.
e.[5]Determine the percentage of homicide deaths caused by handguns.
2.[5]A study of the effect of abortions on the health of subsequent children was conducted as follows. The researchers obtained names of women who had had abortions from medical records in New York City hospitals. They then search birth records to locate all women in this group who bore a child within five years off the abortion. Then hospital records were examined again for information about the health of the newborn child. Was this an observational study or an experiment? Why?
3.Rotter Partners is planning a major investment. The amount of profit X is uncertain but a probabilistic estimate gives the following distribution (in million of dollars):
Profit / 1 / 1.5 / 2 / 4 / 10Probability / 0.1 / 0.2 / 0.4 / 0.2 / 0.1
a.[8]Find the mean profit X and the standard deviation of the profit.
b.[7]Rotter Partners owes its source a capital fee of $200,000 plus 10% of the profits X. So the firm actually retains
Y = 0.9X – 2
from the investment. Find the mean and the standard deviation of Y.
4.Here is the distribution of he adjusted gross income X (in thousands of dollars) reported on individual federal income tax returns in 1993:
Income / < 10 / 10 - 24 / 25 - 49 / 50 - 99 / 100Probability / 0.29 / 0.27 / 0.25 / 0.14 / 0.05
Let A be the event that the adjusted gross income is $50,000 or more and B be the event that the adjusted gross income is less than $50,000.
a.[5]Find P(A)
b.[5]Find P(B)
c.[5]Find P(A or B)
d.[5]The events A and B are ___
a.independentb.mutually exclusive
c.complementaryd.conditional
5.[5]Which of the following is not one of the principles of statistical designs of experiments?
a.controlb.randomization
c.biasd.replication
6.Explain in your own words, the meaning of the following statistical terms:
a.[5]stratified random sample
b.[5]placebo
c.[5]unbiased estimator
d.[5]The mean of a population is 98 and the above histogram is the distribution of the sample taken from the population. What can you say about the variability of the sample above?
7.Anthony, Brandon, Carla, Dana, and Elisa are the top five students in a mathematics class. The teacher wants to send three of the students to a contest and does not want to offend any of the students.
a.[5]List all the possible groups of three that can be sent to the contest.
b.[5]What is the probability that at least one girl will go to the contest?
c.[5]What is the probability the none of the girls will go to the contest.
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STP 420 TEST 2 SUMMER 2001
Copyright Arizona State University Department of Mathematics