WorksheetsConfidence Intervals Proportions
Total questions: 10
Worksheet time: 10mins
Name
Class
Date
1.
What is the point estimator for the interval (-5 , 13)?
a)
10
b)
9.5
c)
9
d)
-5
2.
What is the margin of error for the interval (6.8, 12.9)?
a)
9.85
b)
3.05
c)
3.50
d)
6.8
3.
Which of the following actions would produce a confidence interval with a smaller width assuming all other contingencies remained constant?
a)
Using a higher confidence level
b)
Using a lower confidence level
4.
Which of the following changes to a study would result in a narrower confidence interval?
a)
increasing the confidence level, increasing the sample size
b)
decreasing the confidence level, decreasing the sample size
c)
increasing the confidence level, decreasing the sample size
d)
decreasing the confidence level, increasing the sample size.
5.
A 90% confidence interval for the average salary of all CEOs in the electronics industry was constructed using the results of a random survey of 45 CEOs. The interval was ($139,048, $154,144). Give a practical interpretation of the interval.
a)
90% of the sampled CEOs have salaries that fell in the interval $139,048 to $154,144
b)
We are 90% confident that the mean salary of all CEOs in the electronics industry falls in the interval $139,048 to $154,144.
c)
90% of all CEOs in the electronics industry have salaries that fall between $139,048 to $154,144
d)
We are 90% confident that the mean salary of the sampled CEOs falls in the interval $139,048 to $154,144.
6.
A recent study of 750 Internet users in Europe found that 35% of Internet users were women. What is the 95% confidence interval of the true proportion of women in Europe who use the Internet?
a)
0.321 < p < 0.379
b)
0.316 < p < 0.384
c)
0.309 < p < 0.391
d)
0.305 < p < 0.395
7.
A survey of 800 women shoppers found that 17% of them shop on impulse. What is the 98% confidence interval for the true proportion of women shoppers who shop on impulse?
a)
0.148 < p < 0.192
b)
0.136 < p < 0.204
c)
0.144 < p < 0.196
d)
0.139 < p < 0.201
8.
A researcher at a major hospital wishes to estimate the proportion of the adult population of the U.S. that has high blood pressure. How large a sample is needed in order to be 90% confident that the sample proportion will not differ from the true proportion by more than 5%?
a)
9
b)
271
c)
164
d)
542
9.
It was found that in a sample of 90 teenage boys, 70% of them have received speeding tickets. What is the 90% confidence interval of the true proportion of teenage boys who have received speeding tickets?
a)
(0.621, 0.780)
b)
(0.591, 0.812)
c)
(0.584, 0.830)
d)
(0.615, 0.805)
10.
Which of the following values below represents the critical value for a 98% confidence interval?
a)
2.326
b)
2.054
c)
1.645
d)
3.091
100 %
