Question

At 99% confidence, how large a sample should be taken to obtain a margin of error of .012 for the estimation of a population proportion? Assume that past data are not available for developing a planning value for p*. Round up to the next whole number.

Answer 1

Solution :

Given that,

= 0.5

1 - = 1 - 0.5 = 0.5

margin of error = E = 0.012

At 99% confidence level the z is,

= 1 - 99%

= 1 - 0.99 = 0.01

/2 = 0.005

Z/2 = 2.576 ( Using z table )

Sample size = n = (Z/2 / E)2 * * (1 - )

= (2.576 / 0.012)2 * 0.5* 0.5

=1520.44

Sample size = 1521 rounded