NAME: _______________________________
Worksheet 10.2 B
Complete each problem. Don’t forget to check conditions for confidence intervals and tests of significance. Write all
sentences/conclusions, and include units.
1- Here are the IQ test scores for and SRS of 33 seventh-grade girls in a Midwest School District.
114
100
104
89
102
91
114
114
103
105
109
108
130
120
132
111
128
118
119
86
72
100
111
103
74
112
107
103
98
96
112
112
93
a) Enter the data into your calculator in L1, and then run 1-Var Stats. Record the sample mean ( x ), the sample
standard deviation (Sx), and the sample size (n). Use this info for this problem.
b) Check the conditions
c) Create a 98% confidence interval for the average IQ score for seventh-grade girls.
d) The average IQ score for any age group is supposed to be 100. Use the information in this problem to test and
see if the average IQ score is different from 100. Use α=0.03.
2- Complete #54 on page 514-515 in the textbook.
3- An environmental group collects a liter of water from an SRS of 45 locations along a stream and measures the amount
of contamination in each specimen. The average of the sample is 4.62 milligrams and the standard deviation is 0.92
milligrams.
a) Check the conditions
b) Create a 95% confidence interval for the average amount of contamination in the stream
c) It has been claimed that the contamination level in the stream is 5 milligrams. Using the info in this
problem, test to see if stream’s contamination level has decreased.
8- I have a 94% confidence interval that is (45.6, 59.3).
a) Suggest a possible 98% confidence interval
b) Suggest a possible 91% confidence interval
10- I have a 95% confidence interval that is (32.9, 48.4)
a) What is the sample mean?
b) What is the margin of error?
c) If I increase my confidence to 99%, what will happen to my margin of error and to my confidence interval?
d) If I increase my sample size, what will happen to my margin of error and to my confidence interval?
13- Complete #57 on page 515 in the textbook. Check conditions & then perform a full test of significance.
14- Complete #46 on page 509 in the textbook. Check conditions (you can assume that the population is normally
distributed, so the sample size being less than 30 is ok) & then create and interpret a 95% confidence interval.
EXTRA:
15- A recent study claims that out of all the ice cream flavors, 52% of people say chocolate is their favorite flavor. You
think this is too high! You take a random sample of 115 customers at a local ice cream store and find that only 51 of
them say that chocolate is their favorite. Check the conditions & then test the claim at a significance level of 0.05.
16- A company is marketing its new toy for children ages 3-8, however they are interested in the proportion of 4 to 5year-old children like the toy. They take a SRS of 53 4 to 5-year-old children and perform a series of tests to determine
whether the child likes the toy or not. They determine that of the children in their sample, 28 like their toy. Check the
conditions & then estimate the percent of children that like the toy using a 96% level of confidence. Interpret your
interval.
NAME: _______________________________
Worksheet 10.2 B
Complete each problem. Don’t forget to check conditions for confidence intervals and tests of significance. Write all
sentences/conclusions, and include units.
1- Here are the IQ test scores for and SRS of 33 seventh-grade girls in a Midwest School District.
114
100
104
89
102
91
114
114
103
105
109
108
130
120
132
111
128
118
119
86
72
100
111
103
74
112
107
103
98
96
112
112
93
e) Enter the data into your calculator in L1, and then run 1-Var Stats. Record the sample mean ( x ), the sample
standard deviation (Sx), and the sample size (n). Use this info for this problem.
f) Check the conditions
g) Create a 98% confidence interval for the average IQ score for seventh-grade girls.
h) The average IQ score for any age group is supposed to be 100. Use the information in this problem to test and
see if the average IQ score is different from 100. Use α=0.03.
2- Complete #54 on page 514-515 in the textbook.
3- An environmental group collects a liter of water from an SRS of 45 locations along a stream and measures the amount
of contamination in each specimen. The average of the sample is 4.62 milligrams and the standard deviation is 0.92
milligrams.
d) Check the conditions
e) Create a 95% confidence interval for the average amount of contamination in the stream
f) It has been claimed that the contamination level in the stream is 5 milligrams. Using the info in this
problem, test to see if stream’s contamination level has decreased.
8- I have a 94% confidence interval that is (45.6, 59.3).
c) Suggest a possible 98% confidence interval
d) Suggest a possible 91% confidence interval
10- I have a 95% confidence interval that is (32.9, 48.4)
e) What is the sample mean?
f) What is the margin of error?
g) If I increase my confidence to 99%, what will happen to my margin of error and to my confidence interval?
h) If I increase my sample size, what will happen to my margin of error and to my confidence interval?
13- Complete #57 on page 515 in the textbook. Check conditions & then perform a full test of significance.
14- Complete #46 on page 509 in the textbook. Check conditions (you can assume that the population is normally
distributed, so the sample size being less than 30 is ok) & then create and interpret a 95% confidence interval.
EXTRA:
15- A recent study claims that out of all the ice cream flavors, 52% of people say chocolate is their favorite flavor. You
think this is too high! You take a random sample of 115 customers at a local ice cream store and find that only 51 of
them say that chocolate is their favorite. Check the conditions & then test the claim at a significance level of 0.05.
16- A company is marketing its new toy for children ages 3-8, however they are interested in the proportion of 4 to 5year-old children like the toy. They take a SRS of 53 4 to 5-year-old children and perform a series of tests to determine
whether the child likes the toy or not. They determine that of the children in their sample, 28 like their toy. Check the
conditions & then estimate the percent of children that like the toy using a 96% level of confidence. Interpret your
interval.