Question

Find the minimum sample size n needed to estimate mu for the given values of​ c, sigma​, and E.

c=0.90​, sigma=7.9, and E=2

Assume that a preliminary sample has at least 30 members.

Answer 1

Solution :

Given that,

standard deviation = = 7.9

margin of error = E = 2

At 90% confidence level the z is ,

  = 1 - 90% = 1 - 0.90 = 0.1

/ 2 = 0.1 / 2 = 0.05

Z_/2 = Z_0.05 = 1.645

Sample size = n = ((Z_/2 * ) / E)²

= ((1.645 * 7.9) / 2)²

= 42.2

minimum Sample size = 43