Question

An infinite population has a standard deviation of 10. A random sample of 100 items from this population is selected. The sample mean is determined to be 60. At 80% confidence, the margin of error is

Answer 1

1.28

Explanation:

Margin of error is also called confidence interval, and it shows how much the results from sample reflects the characteristics of the larger population.

The following steps are used to calculate margin of error.

- obtain population standard deviation (σ) and sample size (n)

- divide standard deviation by square root of sample size

- multiply result by z score consistent with the given confidence. In this case confidence is 80% and z score for it is 1.28

Margin of error= z * (σ ÷ √n)

Margin of error = 1.28 * (10 ÷ √100)

Margin of error= 1.28 * (10 ÷ 10) = 1.28