Standardized tests for certain subjects, given to high school students, are scored on a scale of 1 to 5. Let [tex]$X$[/tex] represent the score on a randomly selected exam. The distribution of scores for one subject's standardized test is given in the table.

\begin{tabular}{|c|c|c|c|c|c|}
\hline Score & 1 & 2 & 3 & 4 & 5 \\
\hline Probability & 0.18 & 0.20 & 0.26 & 0.21 & 0.15 \\
\hline
\end{tabular}

What is the probability of earning a score lower than 3?

A. 0.20
B. 0.26
C. 0.38
D. 0.64



Answer :

To determine the probability of earning a score lower than 3, we need to consider the scores that are less than 3. In this case, the scores are 1 and 2.

From the given distribution table:

- The probability of scoring 1 is [tex]\(0.18\)[/tex].
- The probability of scoring 2 is [tex]\(0.20\)[/tex].

To find the total probability of earning a score lower than 3, we sum the probabilities of scoring 1 and 2.

[tex]\[ \text{Probability of scoring 1} + \text{Probability of scoring 2} = 0.18 + 0.20 = 0.38 \][/tex]

Hence, the probability of earning a score lower than 3 is [tex]\(0.38\)[/tex]. Therefore, the correct option is [tex]\(0.38\)[/tex].