Posted by **Monique** on Wednesday, June 11, 2008 at 11:59pm.

The estimate of the population proportion is to be within plus or minus .10, with a 99 percent level of confidence. The best estimate of the population proportion is .45. How large a sample is required?

- Statistics #3 -
**MathGuru**, Thursday, June 12, 2008 at 12:02pm
Here is one formula you might use for this problem:

n = [(z-value)^2 * p * q]/E^2

With your data:

n = [(2.575)^2 * .45 * .55]/.10^2

I'll let you finish the calculation (round to the next highest whole number).

Note: n = sample size needed; .45 for best estimate of the population proportion; .55 for q, which is (1 - p). E = maximum error, which is .10 from the problem. Z-value is found using a z-table (for 99%, the value is 2.575).

I hope this helps.

- Statistics #3 -
**Monique**, Thursday, June 12, 2008 at 4:14pm
THANK YOU

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