Question

What sample size is needed to give a margin of error within +-6 in estimating a population mean with 95% confidence, assuming a previous sample had s=20.
Round your answer up to the nearest integer. sample size = _______.

Answer 1

Answer:

43

Step-by-step explanation:

The formula for Margin of Error =

Margin of Error = z × standard deviation/√n

Margin of Error= ± 6

z = z score of 95% Confidence Interval is 1.96

s = 20

n = sample size

±6 = 1.96 × 20/√n

Cross Multiply

±6 × √n = 1.96 × 20

±6 × √n = 39.2

Divide both sides by ±7

√n = 39.2/±6

√n = 6.5333333333

Square both sides

n = 6.5333333333²

n= 42.684444444

Rounding up to the nearest integer = 43