To find:The classical probability.

Given:
Number of freshmen = 14
Number of sophomores = 21
Number of juniors = 9
Number of seniors = 1
Formula Used:
Let E denote the event of the Professor selecting the senior to answer a question and S denote the sample space. Then, P(E) denotes the probability that E occurs. The probability is given by,
$P(E)=\frac{n(E)}{n(S)}$
Where, n(E) denotes the number of elements in E and n(S) denotes the number of elements in S.
Calculation:
Calculate the total number of students enrolled in the college algebra class.
Total number of students enrolled in the college algebra class = 14+21+9+1=45
The probability that the Professor randomly selects the senior to answer a question is given by,
$P(E)=\frac{n(E)}{n(S)}$
=Number of seniors in class/Total number of students in class
$=\frac{1}{45}\approx 0.0222$