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
