Let x be the duration, in days, of a particular rhinovirus. The distribution of x is approximately normal with a mean
of 7.2
days and a standard deviation of 1.9 days. Use pnorm() or qnorm() to help you find the following.
Find P(x ≤ 5), rounded to three decimal places.
Find P(x > 8.2), rounded to three decimal places.
Find the value that marks the lowest 20% of the duration time, rounded to one decimal place.