Suppose that a population parameter is 0.5 and many large samples are taken from the population. if the sample proportions are normally distributed, with 99.7% of the sample proportions falling between 0.434 and 0.566, what is the standard deviation of the sample proportions? a. 0.025 b. 0.015 c. 0.011 d. 0.022

The margin of error of the 99.7% confidence interval is 
     

This computed margin or error is actually 3 standard deviations from the mean according to the empirical rule. The empirical rule states that 3 standard deviations away from the mean constitute the 99.7%.

Therefore, the value 0.066 is 3 times the standard deviation. The standard deviation, SE, is 
     

The standard deviation is 0.022.