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The NWBC found that 13% of women-owned businesses provided profit-sharing and/or stock options. What sample size could be 98% confident that the estimated (sample) proportion is within 5 percentage points of the true population proportion?

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Answer: We can use the formula for sample size calculation for estimating a population proportion:

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

where:

z = the z-score corresponding to the desired level of confidence

p = the estimated proportion from the population (0.13 in this case)

E = the desired margin of error (0.05 in this case)

Substituting the given values, we get:

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

n = (2.326^2 * 0.13 * (1 - 0.13)) / 0.05^2

n ≈ 319.8

We need a sample size of at least 320 to be 98% confident that the estimated proportion of women-owned businesses providing profit-sharing and/or stock options is within 5 percentage points of the true population proportion.

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