Chapter 7 Estimating Parameters

Question

Listed below are the amounts of mercury​ (ppm) found in tuna sushi sampled at different stores in a major city. Construct a 98​% confidence interval estimate of the mean amount of mercury in the population.

Does it appear that there is too much mercury in tuna​ sushi?

0.51 0.70 0.10 0.86 1.35 0.55 0.90

What is the confidence interval estimate of the population mean mu​?

Answer 1

First you calculate the mean and standard deviation.

The mean = 0.71 and the standard deviation is 0.39.

The sample size is 7 so the degrees of freedom is 6.

The critical t-value of a 98 percent confidence interval and 6 degrees of freedom is 3.143

The formula for the confidence interval for the population mean is:

sample mean (0.71) +/- critical t-value (3.143) * standard deviation (0.39)/square root of sample size (7)

That CI will contain the plausible values of the population mean at a 98% confidence level.

Whether the CI contains values which indicate too much mercury will depend on what the acceptable level of mercury is.