A pharmaceutical company wants to estimate the mean life of a particular drug under typical weather conditions. Following results were obtained from a simple random sample of 64 bottles of the drug:...

Extracted text: A pharmaceutical company wants to estimate the mean life of a particular drug under typical weather conditions. Following results were obtained from a simple random sample of 64 bottles of the drug: Sample mean : 20 months Population standard deviation :3 months Sample size Find an interval estimate with a confidence level of (i) 90%, (ii) 95% and (iii) 99%. :64