SOLUTION: You wish to estimate with a 95% confidence the population proportion of kids who say red is their favorite color. Estimate must be within 5% of population proportion. Find minimum

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Question 981166: You wish to estimate with a 95% confidence the population proportion of kids who say red is their favorite color. Estimate must be within 5% of population proportion. Find minimum sample size.
Answer by jim_thompson5910(35256) About Me  (Show Source):
You can put this solution on YOUR website!
z = 1.96 is the critical value at 95% confidence
E = 5% = 0.05 is the margin of error
Since we don't know p, we make the conservative estimate that p = 0.5


n = p(1-p)(z/E)^2

n = 0.5(1-0.5)(1.96/0.05)^2

n = 384.16

n = 385 ... Round up to the nearest whole number.

The min sample size needed is 385.