4. Why is a 99% confidence interval wider than a 95% confidence interval?
12. A person claims to be able to predict the outcome of flipping a coin. This
person is correct 16/25 times. Compute the 95% confidence interval on the
proportion of times this person can predict coin flips correctly. What
conclusion can you draw about this test of his ability to predict the future.
15. You take a sample of 22 from a population of test scores, and the mean of your
sample is 60. (a) You know the standard deviation of the population is 10.
What is the 99% confidence interval on the population mean. (b) Now assume
that you do not know the population standard deviation, but the standard
deviation in your sample is 10. What is the 99% confidence interval on the
100. What is meant by the term “90% confident” when constructing a confidence interval for a mean?
a. If we took repeated samples, approximately 90% of the samples would produce the same confidence interval.
b. If we took repeated samples, approximately 90% of the confidence intervals calculated from those samples would
contain the sample mean.
c. If we took repeated samples, approximately 90% of the confidence intervals calculated from those samples would
contain the true value of the population mean.
d. If we took repeated samples, the sample mean would equal the population mean in approximately 90% of the
120. An article regarding interracial dating and marriage recently appeared in the Washington Post. Of the 1,709 randomly
selected adults, 315 identified themselves as Latinos, 323 identified themselves as blacks, 254 identified themselves as
Asians, and 779 identified themselves as whites. In this survey, 86% of blacks said that they would welcome a white person
into their families. Among Asians, 77% would welcome a white person into their families, 71% would welcome a Latino,
and 66% would welcome a black person.