Question

A consumer advocate wants to collect a sample of jelly jars and measure the actual weight of the product in the container. He needs to collect enough data to construct a confidence interval with a margin of error of no more than 3 grams with 95​% confidence. The standard deviation of these jars is usually 3 grams. Estimate the minimum sample size required.

Answer 1

The following information is provided,
Significance Level, α = 0.05, Margin or Error, E = 3, σ = 3

The critical value for significance level, α = 0.05 is 1.96.

The following formula is used to compute the minimum sample size required to estimate the population mean μ within the required margin of error:
n >= (zc *σ/E)^2
n = (1.96 * 3/3)^2
n = 3.84

Therefore, the sample size needed to satisfy the condition n >= 3.84 and it must be an integer number, we conclude that the minimum required sample size is n = 4
Ans : Sample size, n = 4