# Question: a A statistics practitioner calculated the mean and standard deviation

a. A statistics practitioner calculated the mean and standard deviation from a sample of 51. They are x̄ = 120 and s = 15. Estimate the population mean with 95% confidence.

b. Repeat part (a) with a 90% confidence level.

c. Repeat part (a) with an 80% confidence level.

d. What is the effect on the confidence interval estimate of decreasing the confidence level?

b. Repeat part (a) with a 90% confidence level.

c. Repeat part (a) with an 80% confidence level.

d. What is the effect on the confidence interval estimate of decreasing the confidence level?

**View Solution:**## Answer to relevant Questions

a. The sample mean and standard deviation from a sample of 81 observations are x̄ = 63 and s = 8. Estimate e with 95% confidence.b. Repeat part (a) with n = 64.c. Repeat part (a) with n = 36.d. Describe what happens to the ...a. A statistics practitioner wishes to test the following hypotheses:H0: µ = 600H1: µ < 600A sample of 50 observations yielded the statistics x̄ = 85 and s = 45. Calculate the test statistic of a test to determine whether ...a. A statistics practitioner randomly sampled 10 observations and found x̄ = 103 and s = 17. Is there sufficient evidence at the 10% significance level to conclude that the population mean is less than 110?b. Repeat part ...A random sample of American adults was asked whether or not they smoked cigarettes. Those who responded affirmatively were asked how many cigarettes they smoked per day. Assuming that there are 50 million American adults who ...Estimate with 95% confidence the mean income (INCOME) of Americans in 2012.Post your question