Question

13

We want to obtain a sample to estimate a population mean. Based on previous evidence, researchers believe the population standard deviation is approximately σ=67.9. We would like to be 99% confident that the esimate is within 1 of the true population mean. How large of a sample size is required?

n=

14

You want to obtain a sample to estimate how much parents spend on their kids birthday parties. Based on previous study, you believe the population standard deviation is approximately σ=63.7 dollars. You would like to be 95% confident that your estimate is within 1.5 dollar(s) of average spending on the birthday parties. How many moms do you have to sample? Do not round mid-calculation.

n =

15

Express the confidence interval 19.9%±5.5% in the form of a trilinear inequality.

% <p< %

Answer 1

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