Find the Specified Probability The Professor Gives Each Student 10 Minutes

Multiple Choice

Find the specified probability.
-A statistics professor has office hours from 9:00 am to 10:00 am each day. The number of students waiting to see the professor is a random variable, X, with the distribution shown in the table. $\begin{array}{c|c|c|c|c|c|c}\mathrm{x} & 0 & 1 & 2 & 3 & 4 & 5 \\\hline \mathrm{P}(\mathrm{X}=\mathrm{x}) & 0.05 & 0.10 & 0.40 & 0.25 & 0.15 & 0.05\end{array}$
The professor gives each student 10 minutes. Determine the probability that a student arriving just after 9:00 am will have to wait no longer than 20 minutes to see the professor.

A) $0.40$
B) $0.55$
C) $0.80$
D) $0.15$