MATH 10 Mr. Michael Leitner Chapters 8-11 Practice Test C NAME ...

MATH 10 Mr. Michael Leitner
Chapters 8-11 Practice Test C
NAME SCORE
Problems are 10 points each.
Remember to show your work and calculator entries.
1. Big O Cereals ran a test of their production line. A random sample of the
contents of 46 boxes of cereal had a mean weight of 22.08 ounces with a
standard deviation of 1.18 ounces. What is the 95% confidence interval
for the actual mean weight of the contents of Big O Cereal boxes?
2. What proportion of people sent a survey will return it if a $1 bill is
included? Without a preliminary survey, how many people should be
surveyed to be 90% confident the estimate will be within 4% of the true
proportion?
3. A survey of 781 restaurant patrons found that 132 preferred decaffeinated
coffee to regular. What is the point estimate for the proportion of patrons
who prefer decaffeinated coffee to regular coffee? What is the margin of
error for this survey based on a 95% confidence interval?

4. Marine biologists studying a rare species of ocean floor worms have
obtained six specimens with the following lengths (in mm):
8.0 7.4 6.2 9.3 7.3 8.6 7.8
What is the estimated mean length of these rare worms? Give a 95%
confidence interval for the actual mean.
5. The following table lists the age and annual repair costs for a sample of ten cars of the same model.
Age 5 3 2 3 1 5 7 7 8 4
Cost $296 $196 $87 $177 $91 $297 $475 $576 $391 $206
a. What annual repair cost would you predict for a car of this model that is 6
years old?
b. Give a 90% confidence interval for your predicted value.
6. Several years ago, a train derailment near Dunsmuir, California, dumped a
carload of soil sterilizing chemicals into the Sacramento River. Prior to
the spill, fish counts averaged 75 fish/hour passing a counting station. The
train company claims that fish have returned to the river to the same level
as before the spill. A sample of 50 counts yields an average of 70
fish/hour with a standard deviation of 16 fish/hour. Test the train
company's claim using a 0.05 level of significance.
Conclusion:
H0:
H1:
P-value:
Reject H0?
Math 10, Chapter 8-11 Practice Test B

7. A story is told of Carl Friedrich Gauss that during the war when flour was
being rationed and everyone was supposed to be getting 200g loaves of
bread, he measured his loaves and after weighing 50 loaves he found they
had an average weight of 195g with a standard deviation of 15g. He
concluded from this that the baker was using less than the required weight
of flour and selling what he skimmed on the black market. To a 0.01 level
of significance, was the baker using less than the required amount of
flour?
Conclusion:
8. A psychologist wants to know if birth order is a factor in the intelligence
of identical twins. Fifteen pairs of twins were given IQ tests with the
results shown in the table below right. Using a 0.05 level of significance,
is there a difference in intelligence based on birth order?
H0:
H1:
P-value:
Reject H0?
H0:
H1:
P-value:
Reject H0?
# Older Younger
1 121 115
2 108 117
3 118 107
4 138 116
5 128 117
Conclusion: 6 125 119
7 106 121
8 138 127
9 108 97
10 118 119
11 105 99
12 95 105
13 114 111
14 122 113
15 127 109
Math 10, Chapter 8-11 Practice Test B

9. Sierra Ski School is testing two new methods for teaching downhill skiing
and wants to know if there is a difference between the two methods. With
method A, 40 students chosen at random were able to ski down Beginner's
Hill after an average of 5.5 hours of lessons with a standard deviation of 1.2
hours. Another 36 randomly selected students were taught with method B
and were able to ski down Beginner's Hill after 6.0 hours of lessons, with a
standard deviation of 1.5 hours. Is there a difference between the two
methods? Use α = 0.05 level of significance to test.
Conclusion:
10. Does a student’s favorite subject depend on gender? The results of a
survey are shown below. Test if a student's favorite subject depends on
gender using α = 0.05 level of significance.
H0:
H1:
P-value:
Reject H0?
Math and Social P-value:
Phys. Science Science Business Humanities
Men 48 44 55 28 Reject H0?
Women 57 61 45 42
Conclusion:
H0:
H1:
Math 10, Chapter 8-11 Practice Test B