Question

Recent study stated that if a person chewed gum, the average number of sticks of gum he or she chewed daily was 8. To test the claim, a researcher selected a random sample of 36 gum chewers and found the mean number of sticks of gum chewed per day was 9. The standard deviation of the population is 1.

a) Find a 95% confidence interval for the average number of sticks of gum he or she chewed daily

b) Explain what does “a 95% confidence” means.

Answer 1

given that n-36 let los be a-oos, z=1.96 a) 95.CI - z 981-96 ( - 9 0.33 - (8.7, 9.33) 6) we are 95% confident that the population mean les between 8.7 8 9.33

Since the confidence interval don't contain 8 , so we reject the claim and we can't conclude that the average number of sticks of gum he or she chewed daily is 8.