U= the 100 people surveyed A= the 60 people that like coca-cola B= the 55 people that like Pepsi C= the 30 people that liked neither

45 people that like both

Step-by-step explanation:

Given

--- coca-cola

--- Pepsi

--- None

Required

People that like both

Represent this set of people with x.

To solve for x, we have:

Total = Coca-Cola only+ Pepsi only + Both + None

Mathematically, we have:

This gives

Remove brackets and collect like terms

Collect like terms

false

step-by-step explanation:

i looked it up

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.