Use the sample information x¯x¯ = 40, ? = 7, n= 13 to calculate the following confidence intervals for ?assuming the sample is from a normal population.
(a) 90 percent confidence. (Round youranswers to 4 decimal places.)
The 90% confidence interval is from _____ to _____
(b) 95 percent confidence. (Round youranswers to 4 decimal places.)
The 95% confidence interval is from _____ to _____
(c) 99 percent confidence. (Round youranswers to 4 decimal places.)
The 99% confidence interval is from _____ to _____
(d) Describe how the intervals change as youincrease the confidence level.
The interval gets narrower as the confidence levelincreases.
The interval gets wider as the confidence level decreases.
The interval gets wider as the confidence level increases.
The interval stays the same as the confidence levelincreases.
