Download Chapter 4 EXTRA PRACTICE

College Prep Stats
Name: _____________________________________
Chapter 4 Review EXTRA PRACTICE
Round answers to the thousandths place, unless otherwise specified.
1. Of the 84 people who answered “yes” to a question, 14 were male. Of the 73 people that answered “no” to the same questions, 12
were male. Fill in the table below and use the table to answer the probability questions.
Responded “yes”
Responded “no”
Total
Male
14
12
26
Female
70
61
131
Total
84
73
157
a) If one person is selected at random from the group, what is the probability that the person was a female?
b) If one person is selected at random from the group, what is the probability that the person answered “yes” or was male?
c) If one person is selected at random from the group, what is the probability that the person answered “yes” and was male?
d) If one person is selected at random from the group, what is the probability that the person answered “no” or was female?
e) If two people are selected at random from the group, what is the probability that the first person answered yes and the second
person answered no? (assume without replacement)
f) If two people are selected at random from the group, what is the probability that both of them were males? (assume without
replacement)
2. An allergist conducts a study to determine allergies to cats.
Allergic
Positive
139
Negative
27
Total
166
Not Allergic
16
297
313
Total
155
324
479
a) If one of the test subjects is randomly selected, find the probability that the subject tested positive or was allergic to cats.
b) If one of the test subjects is randomly selected, find the probability that the subject was not allergic to cats.
c) Find the probability of a false negative or a false positive.
3. All of the letters of the alphabet are written on identical slips of paper and placed into a hat and mixed up really well. Find
a) P(selecting one slip of paper and it having a vowel written on it). Do not include Y as a vowel.
b) P(selecting one slip of paper and it having a consonant written on it).
c) P(L or Q).
4. If you are told that a mystery person's name begins with a consonant, would it be "unusual" to guess the first letter of that person's
name?
5. In a certain class of students, there are 10 boys from Wilmette, 6 girls from Kenilworth, 6 girls from Wilmette, 5 boys from
Glencoe, 3 boys from Kenilworth and 5 girls from Glencoe. If the teacher calls upon a student to answer a question, what is the
probability that the student will be from Kenilworth?
6. In one town, 39% of all voters are Democrats. If two voters are randomly selected for a survey, find the probability that they are
both Democrats.
7. In a batch of 8,000 clock radios 5% are defective. A sample of 14 clock radios is randomly selected without replacement from the
8,000 and tested. The entire batch will be rejected if at least one of those tested is defective. What is the probability that the entire
batch will be rejected?
8. A medical testing laboratory saves money by combining blood samples for tests. The combined sample tests positive if at least one
person is infected. If the combined sample tests positive, then the individual blood tests are performed. In a test for Chlamydia, blood
samples from 10 randomly selected people are combined. Find the probability that the combined sample tests positive with at least one
of the 10 people infected. Based on data from Centers for Disease Control, the probability of a randomly selected person having
Chlamydia is 0.00320. Is it lik