Answer the
following problems showing your work and explaining (or analyzing) your
results.
1.
The
math grades on the final exam varied greatly. Using the scores below, how many
scores were within one standard deviation of the mean? How many scores were within
two standard deviations of the mean?
99 34 86 57 73 85
91 93 46
96 88 79
68 85 89
2.
The
scores for math test #3 were normally distributed. If 15 students had a mean
score of 74.8% and a standard deviation of 7.57, how many students scored above
an 85%?
3.
If you
know the standard deviation, how do you find the variance?
4.
To get
the best deal on a stereo system, Louis called eight appliance stores and asked
for the cost of a specific model. The prices he was quoted are listed below:
$216 $135 $281 $189 $218 $193 $299 $235
Find the standard deviation.
5.
A
company has 70 employees whose salaries are summarized in the frequency
distribution below.
|
Salary
|
Number
of Employees
|
|
5,001–10,000
|
8
|
|
10,001–15,000
|
12
|
|
15,001–20,000
|
20
|
|
20,001–25,000
|
17
|
|
25,001–30,000
|
13
|
- Find the standard deviation.
- Find the variance.
6. Calculate the mean
and variance of the data. Show and explain your steps. Round to the
nearest tenth.
14, 16, 7, 9, 11, 13, 8, 10
7. Create a frequency distribution table for the number of
times a number was rolled on a die. (It may be helpful to print or write out
all of the numbers so none are excluded.)
3, 5, 1, 6, 1, 2, 2, 6, 3, 4, 5, 1, 1, 3, 4, 2, 1, 6, 5, 3, 4, 2, 1, 3, 2, 4, 6, 5, 3, 1
8.
Answer
the following questions using the frequency distribution table you created in
No. 7.
- Which number(s) had the highest
frequency?
- How many times did a number of
4 or greater get thrown?
- How many times was an odd
number thrown?
- How many times did a number
greater than or equal to 2 and less than or equal to 5 get thrown?
9.
The
wait times (in seconds) for fast food service at two burger companies were
recorded for quality assurance. Using the data below, find the following for
each sample.
- Range
- Standard deviation
- Variance
Lastly, compare the two sets of
results.
|
Company
|
Wait times in seconds
|
|||||||
|
Big Burger Company
|
105
|
67
|
78
|
120
|
175
|
115
|
120
|
59
|
|
The Cheesy Burger
|
133
|
124
|
200
|
79
|
101
|
147
|
118
|
125
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
10. What does it mean if a graph is normally distributed? What
percent of values fall within 1, 2, and 3, standard deviations from the mean?
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