1. A political candidate has asked you to conduct a poll to
determine what percentage of people support her. If the candidate
only wants a 9% margin of error at a 95% confidence level, what
size of sample is needed? Use the basic confidence interval
formula, not the more accurate +4 adjustment. Give your answer in
whole people.
2. You intend to estimate a population mean with a confidence
interval. You believe the population to have a normal distribution.
Your sample size is 5.
Find the critical value that corresponds to a confidence level of
98%.
(Report answer accurate to three decimal places with
appropriate rounding.)
ta/2 = ±
3. Express the confidence
interval 89.6%±3.5%89.6%±3.5% in the form of a trilinear
inequality.
% < p
< %
4. In a survey, 24 people were asked how much they spent on
their child's last birthday gift. The results were roughly
bell-shaped with a mean of $42 and standard deviation of $8.
Construct a confidence interval at a 99% confidence level.
Give your answers to one decimal place.
±