assist with questions 1-6

work through a numerical process that essentially validates and "proves" the infamous 3 sigma rule. Now, as it is known, the theory states that 99% of the data falls within 3 standard deviations of the mean, but where does that come from, and how is that formal result obtained? Question 1 For a standard normal density ( e.g. normal density with u = 0 and o? = 1 ) set up, but do not compute, an integral to find the arbitrary probability P (-A