A researcher is interested in estimating the mean weight of a semi tracker truck to determine the potential load capacity.She takes a random sample of 17 trucks and computes a sample mean of 20,000 pounds with sample standard deviation of 1,500.The 95% confidence interval for the population mean weight of a semi tracker truck is ______________.
A) 19,232 to 20,768
B) 19,365 to 20,635
C) 19,229 to 20,771
D) 19,367 to 20,633
E) 119.89 to 122.12 18,500 to 21,500

Question

Quizplus · Accepted Answer

The formula for the confidence interval is:sample mean +/- (z-score * standard error)where the z-score is the critical value from the standard normal distribution corresponding to the desired confidence level, and the standard error is the standard deviation of the sample divided by the square root of the sample size.For a 95% confidence level, the z-score is 1.96. The standard error is 1,500 / sqrt(17) = 278.46.Therefore, the confidence interval is:20,000 +/- (1.96 * 278.46) = (19,232, 20,768)

A Researcher Is Interested in Estimating the Mean Weight of a Semi