Measures of Central Tendency 2
Solve the following problems, showing your
work:
1.
In a poll, respondents were asked whether they had ever been in a
car accident. 177 respondents indicated that they had been in a car accident
and 107 respondents said that they had not been in a car accident. If one of
these respondents is randomly selected, what is the probability of getting
someone who has been in a car accident?
Total number of sample or population of
respondents
=107+177=284
Probability someone was in an accident=n/N
Where n=part of the population involved in
accident
And N=
the entire population or sample size
177/284=0.62
2.
The data set represents the income levels of the members of a
country club. Find the probability that a randomly selected member earns at
least $102,000
INCOME (Thousands of dollars)
108 128 82 138 85 108 88 76 158 208
79 98 148 85 128 118 88 168 73 118
INCOME (Thousands of dollars)
108 128 82 138 85 108 88 76 158 208
79 98 148 85 128 118 88 168 73 118
For this problem we
arrange the data in ascending order as follows
73,76,79,82,85,85,88,88,98,108,108,118,118,128,138,148,
158,168, 208
From this point we
determine our n and N as defined above
N is the total number of population or sample
while n is the number of occurrences in the total outcomes we are interested
in.
N=20, n=11
Probability to get over 102,000 salary for the
members=
11/20=0.55
3.
In a certain class of students, there are 13 boys from Wilmette, 3
girls from Kenilworth, 11 girls from Wilmette, 6 boys from Glencoe, 5 boys from
Kenilworth and 6 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?
Wilmette Kenilworth Glencoe total
Boy 13 5 6 24
Girls 11 3 6 20
Total student population=44
Total from kenilworth=8
Probability =8/44=0.18
4.
Find the probability of correctly answering the first 2 questions
on a multiple choice test if random guesses are made and each question has 4
possible answers.
Total answers =8
The first two answers=2
Probability =2/8=0.25
5.
Of 1906 people who came into a blood bank to give blood, 300
people had high blood pressure. Estimate the probability that the next person
who comes in to give blood will have high blood pressure.
Total number=1906
Those with blood pressure=300
Probability=300/1906=0.15
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