Question

4.2. Q: In a study on a 99% confidence interval on IQ scores (Data with mean µ =100 and standard deviation σ = 15), the researcher would like to achieve a margin error of 3 IQ score units. Find the number, n, of IQ scores that should be sampled to achieve that error? Answer: A: 120; B: 166; C: 97; D: 216

Answer 1

solution :

Given that,

standard deviation =   =15

Margin of error = E = 3

At 99% confidence level the z is,

= 1 - 99%

= 1 - 0.99 = 0.01

/2 = 0.005

Z/2 = 2.58

sample size = n = [Z/2* / E] 2

n = ( 2.58* 15 / 3 )2

n =166

Sample size = n =166