For a confidence interval with level C, the value p is equal to (1-C)/2. A 95% confidence interval for the standard normal distribution, then, is the interval (-1.96,1.96), since 95% of the area under the curve falls within this interval. <span>The point estimate for the </span>population proportion<span> is the sample proportion, and the margin of error is the product of the Z value for the desired confidence level (e.g., Z=1.96 for </span>95%<span> confidence) and the standard error of the point </span>
A 95% confidence interval for a population mean is computed from a sample of size 400. Another 95% confidence interval will be computed from a sample of size 100 drawn from the same population. Choose the best answer to fill in the blank: The interval from the sample of size 400 will be approximately _______as the interval from the sample of size 100.
