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Math 221
**** Example Format ****
Week 2 Lab
Submitted by: (Insert Name Here **REMOVE THIS NOTE PRIOR TO
SUBMITTING**)
(Note: Your labs should be well organized, with results clearly identified and in the
proper order. When answering questions, be sure to use complete sentences and proper
grammar. It is also important for you to fully explain your answers! Please do not
answer “yes” (or “no”); you should explain why the answer is “yes”. **REMOVE THIS
NOTE PRIOR TO SUBMITTING**)
Part 1. Random Sampling
Ordered
Sample
AA
AF
AK
AO
AP
AQ
AR
AV
AX
AY
BJ
BO
BQ
BV
CD
CE
CG
CI
CN
CV
The auditor should randomly select files because there is a cost-benefit tradeoff. It takes
too much time and money to audit all the files. Knowing how to take a random sample
and make inferences about the population is an essential tool for auditing.
Part 2. Cereal and Fiber Type
Cereals By Fiber/Serving
Low Fiber
Medium Fiber
Frequency
High Fiber
0
10
20
30
40
Cereals By Fiber/Serving
High Fiber
Medium Fiber
Low Fiber
Part 3. Milk Production
1. Find the sample mean.
2270.54
2. Find the sample standard deviation.
653.18
3. Make a frequency distribution for the data. Distribution is started at right.
Milk Production
Class Limits
1147
1646
1647
2146
2147
2646
2647
3146
Frequency
7
15
13
11
Midpoint
1396.5
1896.5
2396.5
2896.5
Cumulative
Frequency
7
22
35
46
3147
3647
4147
3646
4146
4646
3
0
1
3396.5
3896.5
4396.5
49
49
50
4. Create a histogram for the data. Does the data appear bell-shaped?
Milk Production
16
14
12
10
8
6
4
2
0
1646
2146
2646
3146
3646
4146
4646
No. The data appears to be skewed to the right.
5. What true percent of the data lies within one standard deviations of the mean?
Within two standard deviations of the mean? How do these results agree with the
Empirical Rule?
Within one standard deviation, 74% (Empirical rule says 68%)
Within two standard deviations, 98% (Empirical rule says 95%)
These results aren’t exactly the same as the empirical rule, but they are very close.
6. Find the median of the milk production.
2207
7. Find the maximum and the minimum value.
Minimum: 1147, Maximum: 4285
8. What is the range?
3138
9. What is the first Quartile?
1798.25
10. What is the second Quartile? (What is this also called?)
This is also called the median. 2207
11. What is the third Quartile?
2727.5
12. What is the 80th percentile?
2812.4
Part 4. Linear Regression
Sugar and Calories Analysis
Sugar and Calories
300
Calories
250
y = 4.0934x + 105.03
200
r = 0.552
150
100
50
0
0
10
20
30
Sugar
There is a moderate positive relationship between sugar and calories.
Sugar and Cost Analysis
Sugar and Cost
60
50
y = 0.6987x + 20.791
Cost
40
r = 0.471
30
20
10
0
0
10
20
30
Sugar
There is a moderate positive relationship between sugar and cost.
Weight and Cost Analysis
Weight and Cost
60
y = 16.971x + 3.3162
50
Cost
40
r = 0.831
30
20
10
0
0.00
1.00
2.00
3.00
Weight
There is a strong positive relationship between weight and cost.
(Place your answers in the appropriate position. Format them so that they are clearly
shown. See the worksheet Linear Regressionfrom the Week2Lab.xls file for details.
Be sure to follow the examples given in the files linked from our course for detailed
instructions. Be sure to answer all questions using complete sentences and clearly
explain yourself. **REMOVE THIS NOTE PRIOR TO SUBMITTING**)