Question

We take a sample of the weights of 350 pieces of candy, and we find an average weight of 3 ounces. We know that the population standard deviation of candy is 10 ounces. What is the 90% confidence interval?

Group of answer choices

(1.77, 4.23)

(2.95, 3.05)

(2.5, 3.5)

(2.12, 3.88)

Answer 1

One-Sample Z test Confidence Interval

We need to construct the 90% confidence interval for the population mean μ. We have been provided with the following information: The sample mean is Xˉ=3, the population standard deviation is σ=10, the sample size is n=350, and the significance level is α=0.1 Critical Value Based on the information provided, the significance level is α=0.1, therefore the critical value is Zc​=1.6449. This can be found by either using excel or the Z distribution table. Margin of Error The confidence interval: Therefore, based on the data provided, the 90% confidence interval for the population mean is 2.1208<p<3.8792, which indicates that we are 90% confident that the true population mean μ is contained by the interval