Write down your answers and codes in a R Markdown file (.rmd) using the RStudio, then generate a PDF file. Upload the R Markdown file and the PDF. The distribution of a professor’s quiz scores is...

Write down your answers and codes in a R Markdown file (.rmd) using the RStudio, then
generate a PDF file. Upload the R Markdown file and the PDF.

The distribution of a professor’s quiz scores is normally distributed with a mean of 60 points and
a standard deviation of 15 points. The professor promises his students that the top 20% of the
scores will receive a grade of A in his class.
(a) What is the minimum score you must achieve to receive an A in the class?
(b) Sketch the graph and shade the concerned region.