Question

Height data, collected from a statistics class, has a mean x=68.21 inches, and a standard deviation of s= 4.01 inches. The sample size of the data was n=36 . Suppose the data collected could be considered a random sample of UCLA students.

What sample size would be needed for a 90% confidence interval to have a margin of error,B , within .25?

Give your answer as a whole number.

Answer 1

Solution :

Given that,

standard deviation =s =   =4.01

Margin of error = E = 0.25

At 90% confidence level of z is

= 1 - 90%  

= 1 - 0.90 =0.10

/2 = 0.05

Z/2 = Z0.05 = 1.645

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

n = ( 1.645 * 4.01 / 0.25 )2

n =696.21

Sample size = n =696