Question

Find the sample size needed to estimate the percentage of California residents who are left handed. Use a margin of error of three percentage points and use a confidence level of 99%. Assume that p and q are unknown.

Answer 1

Solution :

Given that,

= 0.5

1 - = 0.5

margin of error = E = 3% = 0.03

At 99% confidence level the z is,

= 1 - 99%

= 1 - 0.99 = 0.01

/2 = 0.005

Z/2 = 2.58    ( Using z table )

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

= (2.58 / 0.03)2 * 0.5 * 0.5

=1849

Sample size = 1849