11) A recent study of 900 internet users in Europe that 20% of internet users were women. What is the 99.5 confidence interval of the true proportion, p, of women in Europe who use the internet?
a) 0.178<p<0.222
b) 0.174<p<0.226
c) 0.171<p<0.229
d) 0.169<p<0.231
e) 0.166<p<0.234
f) 0.163<p<0.237
g) none of these
12) The manager of the dairy store wants to determine the proportion of people who buy mil each day, 150 out of 250 bought milk. What is the 90% confidence interval for the true proportion, p, of customers who buy milk each day?
a) 0.549<p<0.651
b) 0.544<p<0.666
c) 0.539<p<0.661
d) 0.528<p<0.672
e) 0.520<p<0.680
f) 0.513<p<0.687
g) none of these
13) The utility company wishes to estimate the percentage of people in the U.S. who use electricity to heat their homes. Past date indicates that 154 out of 700 customers surveyed used electricity to heat their homes. If the company wishes to be 99% confident to within 3%, how large a sample would be needed?
a) 516
b) 533
c) 854
d) 1032
e) 1266
f) 1503
g) 2066
h) none of these
14) What is the value for X square right for a 90% confidence interval when n = 22?
a) 32.671
b) 35.172
c) 35.479
d) 38.076
e) 38.932
f) 41.401
g) 41.638
h) 44.181
i) None of these
15) What is the value for X square left for a 98% confidence interval when n = 22?
a) 8.034
b) 8.897
c) 9.262
d) 10.196
e) 10.283
f) 11.591
g) 11.689
h) 13.091
I) none of these
16) What is the 98% confidence interval for the standard deviation , σ, of birth weights at County General Hospital, if the standard deviation of the last 22 babies born there was 1.5 pounds? Keep two decimal place accuracy, please.
a) 1.20< σ <2.02
b) 1.15< σ<2.14
c) 1.10< σ<2.30
d) 1.07< σ<2.43
e) 1.28< σ<2.91
f) 1.32< σ<2.77
g) none of these
17) It was found that in a sample of 80 teenage boys, 70% had gotten speeding tickets. What is the 98% confidence interval of the true proportion, p, of teenage boys who have gotten speeding tickets?
a) 0.544<p<0.856
b) 0.616<p<0.784
c) 0.600<p<0.800
d) 0.581<p<0.819
e) 0.568<p<0.832
f) 0.556<p<0.844
g) none of these
18) The average weight of 60 randomly selected compact automobiles was 2620 pounds. The sample deviation was 430 pounds. What is the 99.5 confidence interval of a true mean weight, m, in pounds, of the automobiles?
a) 2529<m<2711
b) 2511<m<2729
c) 2491<m<2749
d) 2483<m<2757
e) 2477<m<2763
f) 2464<m<2776
g) none of these
19) A random sample of 20 fish were taken the days catch of fish in Toxic Bay and the mean level, m, of a chemical herbicide in their blood was found to be 20 parts per million with a standard deviation of 1.2 parts per million. Find the 98% confidence interval of the true mean.
a) 18.6<m<20.4
b) 19.5<m<22.5
c) 20.4<m<22.6
d) 19.3<m<20.7
e) 18.2<m<19.8
f) 20.1<m<20.9
g) none of these
20) A random sample of 40 rolls of 5/16 inch diameter aircraft cable was taken from the recent production of the Calamity Cable Company. A piece was selected from each roll and fastened into a mechanical stretcher wich could read the force wich broke the cable. The mean of the 40 samples was 517 pounds with a sample standard deviation of 44 pounds. What is the 99.5% confidence level of the true mean, m, of the breaking strength of that kind of CCC’s cable.
a) 510<m<524
b) 506<m<528
c) 501<m<533
d) 499<m<535
e) 497<m<537
f) none of these