RESEARCH METHODOLOGY

Detailed explanation-1: -For a population with unknown mean and known standard deviation, a confidence interval for the population mean, based on a simple random sample (SRS) of size n, is + z*, where z* is the upper (1-C)/2 critical value for the standard normal distribution.

Detailed explanation-2: -Since 95% of values fall within two standard deviations of the mean according to the 68-95-99.7 Rule, simply add and subtract two standard deviations from the mean in order to obtain the 95% confidence interval.

Detailed explanation-3: -A 95% confidence interval is a range of values above and below the point estimate within which the true value in the population is likely to lie with 95% confidence. The other 5% is the possibility that the true value is not within the confidence interval.