Question

The standard deviation for SAT tests is known to be 100. Zoe takes a sample of 64 people and calculates a 99% confidence interval. How big is her margin of error

Answer 1

32.2

Explanation:

Margin of Error = Zcritical * √(σ² / n)

σ = standaed deviation. ; sample size = 64

α = 99%

Zcritical at 99% confidence interval = 2.576

Margin of Error = 2.576 * √(100^2/64)

Margin of Error =2.576* 100/8

Margin of error = 2.576 * 12.5

= 32.2