MATH 221 FINAL EXAM REVIEW ( VERSION 1) DEVRY UNIVERSITY
1) Jack weighs 160 pounds and his sister weighs 110 pounds. If the mean weight for
men his age is 175 with a standard deviation of 14 pounds and the mean weight for
women is 145 with a standard deviation of 10 pounds, determine whose weight is closer
to "average." Write your answer in terms of zscores and areas under the normal curve.
x − µ 160 − 175 − 15
for Jack z = = = ≈ −1 . 07 , when z = 1.07, area = .1423
σ 14 14
x − µ 110 − 145 − 25
for his sister = = = −2 . 50 , when z = 2.50, area = .0062
σ 10 10
Jack is closer to average, but he is still in the lower 14%, while his sister is in the bottom less
than 1% of the population.
2) Explain the difference between a population and a sample. In which if these is it
important to distinguish between the two in order to use the correct formula? mean;
median; mode; range; quartiles; variance; standard deviation.
A sample is a subset of a population. A population consists of every member of a particular
group of interest. The variance and the standard deviation require that we know whether we
have a sample or a population.
3) The following numbers represent the weights in pounds of six 7year old children
in Mrs. Jones' 2nd grade class.
{25, 60, 51, 47, 49, 45}
Find the mean; median; mode; range; quartiles; variance; standard deviation.
mean = 46.166....
median = 48
mode does not exist
range = 35
Q1 = 45
Q2 = median = 48
Q3 = 51
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, variance = 112.1396
standard deviation =10.59
4) The Student Services office did a survey of 500 students in which they asked if the
student is parttime or fulltime. Another question asked whether the student was a
transfer student. The results follow.
Transfer NonTransfer Row Totals
PartTime 100 110 210
FullTime 170 120 290
Column Totals 270 230 500
a) If a student is selected at random (from this group of 500 students), find the
probability that the student is a transfer student. P (Transfer)
The total number of transfer students is 270.
The total number of students in the survey is 500
P(Transfer) = 270/500 = .54
b) If a student is selected at random (from this group of 500 students), find the
probability that the student is a part time student. P (Part Time)
The total number of part time students is 210.
The total number of students in the survey is 500.
This study source was downloaded by 100000841990434 from CourseHero.com on 04-29-2022 23:04:03 GMT -05:00
https://www.coursehero.com/file/12432/Math-221-Final-Exam-Review-wanswers/
1) Jack weighs 160 pounds and his sister weighs 110 pounds. If the mean weight for
men his age is 175 with a standard deviation of 14 pounds and the mean weight for
women is 145 with a standard deviation of 10 pounds, determine whose weight is closer
to "average." Write your answer in terms of zscores and areas under the normal curve.
x − µ 160 − 175 − 15
for Jack z = = = ≈ −1 . 07 , when z = 1.07, area = .1423
σ 14 14
x − µ 110 − 145 − 25
for his sister = = = −2 . 50 , when z = 2.50, area = .0062
σ 10 10
Jack is closer to average, but he is still in the lower 14%, while his sister is in the bottom less
than 1% of the population.
2) Explain the difference between a population and a sample. In which if these is it
important to distinguish between the two in order to use the correct formula? mean;
median; mode; range; quartiles; variance; standard deviation.
A sample is a subset of a population. A population consists of every member of a particular
group of interest. The variance and the standard deviation require that we know whether we
have a sample or a population.
3) The following numbers represent the weights in pounds of six 7year old children
in Mrs. Jones' 2nd grade class.
{25, 60, 51, 47, 49, 45}
Find the mean; median; mode; range; quartiles; variance; standard deviation.
mean = 46.166....
median = 48
mode does not exist
range = 35
Q1 = 45
Q2 = median = 48
Q3 = 51
This study source was downloaded by 100000841990434 from CourseHero.com on 04-29-2022 23:04:03 GMT -05:00
https://www.coursehero.com/file/12432/Math-221-Final-Exam-Review-wanswers/
, variance = 112.1396
standard deviation =10.59
4) The Student Services office did a survey of 500 students in which they asked if the
student is parttime or fulltime. Another question asked whether the student was a
transfer student. The results follow.
Transfer NonTransfer Row Totals
PartTime 100 110 210
FullTime 170 120 290
Column Totals 270 230 500
a) If a student is selected at random (from this group of 500 students), find the
probability that the student is a transfer student. P (Transfer)
The total number of transfer students is 270.
The total number of students in the survey is 500
P(Transfer) = 270/500 = .54
b) If a student is selected at random (from this group of 500 students), find the
probability that the student is a part time student. P (Part Time)
The total number of part time students is 210.
The total number of students in the survey is 500.
This study source was downloaded by 100000841990434 from CourseHero.com on 04-29-2022 23:04:03 GMT -05:00
https://www.coursehero.com/file/12432/Math-221-Final-Exam-Review-wanswers/
