Chapter 3 Review Sheet:
1) Based on the following data:
12
45
36
118
50
7
20
a) Find the range.
b) Find the sample mean.
c) Find the sample standard deviation.
d) Find the mode.
e) Find the median.
2) Marjorie is doing a study on her living expenses. Monthly totals for the last year were
(in dollars):
1,300 1,160 1,380 1,440 1,000 3,500 900
1,050 1,220 1,120 1,300
880
a) Find the mean of the data.
b) Find a 10% trimmed mean foe the data.
3) Rollflex and Morgan Trust are two stocks traded on the NYSE. For the past seven
weeks you recorded the Friday closing price (dollars per share)
Rollflex:
21
20
20
23
24
20
25
Morgan Trust: 53
51
50
50
50
55
54
a) Compute the mode, median, and mean for Rollflex.
b) Compute the mode, median, and mean for Morgan Trust.
c) Compute the range, sample standard deviation, and sample variance
for Rollflex.
d) Compute the range, sample standard deviation, and sample variance
for Morgan Trust.
e) Compute the coefficient of variation for both Rollflex and Morgan
Trust. Compare the results and explain the meaning of these numbers.
4) A veterinarian tells you that the mean life span of an Appaloosa horse is 19 years with
a standard deviation of 2 years.
a) Use Chebyshev's Theorem to find an interval for the number of years in which
at least 75% of the Appaloosa life spans will fall.
b) Use Chebyshev's Theorem to find an interval for the number of years in which
at least 93.8% of the Appaloosa life spans will fall.
5) Complete the table below and answer the questions that follow:
a) Calculate the mean.
b) Calculate the standard deviation.
Class
0-2
3-5
6-8
9 - 11
12 - 14
15 - 17
18 - 20
x
f
1
4
7
10
13
16
19
Σ=
xf
Σ=
x–x
bar
(x – x bar)2
(x – x bar)2
(x – x bar)2f
Σ=
6) In the French classes at UNC a standard weighting is given to the required activities in
all sections. These weights are final exam = 40%, midterm = 30%, attendance = 10%,
and language lab = 20%. Each of the four activities is graded on a 100-point scale.
George earned 93 points on the final, 82 points on the midterm, 75 points on attendance,
and 80 points on the language lab. Compute his overall weighted average in his French
class.
7) Counts of white cells in blood were done for 30 blood samples. The number of white
cells (in thousands) per cubic millimeter of blood in each sample was:
3.8
5.7
6.3
4.9
5.2
7.2
5.0
9.5
8.1
7.3
10.1
9.2
6.1
10.0 5.7
8.4
9.6
7.7
5.8
8.7
6.9
8.1
7.5
4.2
8.2
4.9
7.1
7.6
8.9
4.9
a) Give a five-number summary for the data.
b) Make a box-and-whisker plot of the ages.
c) Find the inter-quartile range.