To find the probability that a randomly selected student earned a C or better, we need to consider the grades that correspond to C or better. According to the provided table:
- A grade of [tex]\(4\)[/tex] corresponds to an A.
- A grade of [tex]\(3\)[/tex] corresponds to a B.
- A grade of [tex]\(2\)[/tex] corresponds to a C.
We won't consider grades below C (i.e., 1 for D and 0 for F).
Now we need to find the probabilities of the grades that are C or better, which are 4, 3, and 2. According to the table, the probabilities are:
- The probability of getting an A (grade 4) is 0.43.
- The probability of getting a B (grade 3) is 0.31.
- The probability of getting a C (grade 2) is 0.17.
To find the total probability that a randomly selected student earned a C or better, we sum these probabilities up:
[tex]\[
\text{Probability (C or better)} = \text{Probability (A)} + \text{Probability (B)} + \text{Probability (C)}
\][/tex]
Substituting the given probabilities:
[tex]\[
\text{Probability (C or better)} = 0.43 + 0.31 + 0.17
\][/tex]
Adding these values together:
[tex]\[
0.43 + 0.31 + 0.17 = 0.91
\][/tex]
Thus, the probability that a randomly selected student earned a C or better is [tex]\(0.91\)[/tex].
So, the correct answer is [tex]\(\boxed{0.91}\)[/tex].
