You decide to investigate the weight of all adults men.
You know that weight of all adult men in population is distributed normally with unknown mean and standard deviation of 20 lbs. You then gather a sample of 16 adult men, evaulate their weight and computes their average weight to be 190 lbs.
a) Develop a 95% confidence interval for the true mean weight of all adult men. Also a 90% and 99% CI.
b) How many adult men would you need to sample to ensure that the maximal margin of error for the 95% confidence interval was 20 lbs?