SOLUTION: A researcher wants to determine a 95% confidence interval for the mean number of hours that high school student spend doing homework per week. She know that the standard deviation

Question 1131235: A researcher wants to determine a 95% confidence interval for the mean number of hours that high school student spend doing homework per week. She know that the standard deviation or hours spent per week by all high school students are 7. How large a sample should the researchers select so that the estimated will be within 1.5 hours of the population mean?
Answer by Boreal(15235) (Show Source): You can put this solution on YOUR website!
sd is known so use z
half interval is 1.5, and that is z*sigma/sqrt(n)
95% CI for z=+/-1.96
1.96*7/sqrt(n)=1.5
13.72^2/n=2.25

n=83.66 or 84

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