How many different three letter initials can a person have, if the first and last initial
cannot be the same?
*note: i'm pretty sure the answer looks something like 26! / i'm supposed to understand this using factorials. i don't understand how to get the denominator.

26*26*25 = 16,900

Step-by-step explanation:

First, we focus on the first initial, we have 26 letters that could fit in (the whole alphabet).

In the last initial we can't have the same we have in the first one, so we have 25 letters (the whole alphabet minus the letter that we already choose in the first initial ).

We have no restrictions for the middle one, so again we have 26 letters that could fit in.

So, we have 26*26*25 combinations (we multiply them because they happen all at the same time)

There is no need to use factorials, but we can use them if you want to.

Let's notice that 26! = 26*25*24*23*22*...

In our calculation, we only need the two first factors, so we can divide by 24! =24*23*22*21*...

Therefore,

26*26*25 = 26 * 26! /24!

lol

step-by-step explanation:

introduction, methodology, results, discussion

step-by-step explanation:

an observational study is one which consists of actual observation to record data and then analyse the data.

there are a number of factors that should be analyzed before starting an observational study.

the main four factors are:

i) introduction:   this should be analysed to check whether the purpose of the study is correctly established and the data recorded are appropriate for the study

methodology:   the method of collecting the data, such as whether randomly selected, and whether sample size matches with the population to be studied, whether questions asked are easy to answer by common men, etc.

results: then results such as summary of data with comments should be studied thoroughly

discussion:   the last is the discussion, this can be either by management people or persons who are all interested , etc.