Eight hundred dentists were surveyed about the toothpaste they would recommend to their patients. The survey results are shown in the table below. Dentists Survey Results
Toothpaste Number Recommended
W 280
X 165
Y 210
Z 145
Which of these could a commercial accurately state about the results of the survey?
Select one:

More than half of the dentists recommended toothpaste W and Y.

More than twice as many dentists recommended toothpaste W over Z.

More dentists recommended toothpaste Z over Y.

Four out of five dentists recommended one of the toothpastes.

More dentists recommended toothpaste Z over Y.

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.

reduce the friction between its moving parts

step-by-step explanation:

in fact, by reducing the friction between the moving parts of the machine, it is possible to reduce the energy wasted due to this friction; therefore, more input energy is converted into useful work, and this will improve the efficiency of the machine.