A teacher asks her students to write down the number of hours studied, rounded to the nearest half hour. She compiles the results and develops the probability distribution below for a randomly selected student. What is the mean of the probability distribution?

\begin{tabular}{|c|c|}
\hline
\multicolumn{2}{|c|}{Probability Distribution} \\
\hline
\begin{tabular}{c}
Hours \\
Studied: [tex]$X$[/tex]
\end{tabular} & Probability: [tex]$P ( X )$[/tex] \\
\hline
0.5 & 0.07 \\
\hline
1 & 0.2 \\
\hline
1.5 & 0.46 \\
\hline
2 & 0.2 \\
\hline
2.5 & 0.07 \\
\hline
\end{tabular}



Answer :

To find the mean of the probability distribution, we will calculate the expected value of the number of hours studied. The expected value [tex]\( E(X) \)[/tex] of a discrete random variable [tex]\( X \)[/tex] is given by the formula:

[tex]\[ E(X) = \sum [X_i \cdot P(X_i)] \][/tex]

Where:
- [tex]\( X_i \)[/tex] represents the number of hours studied.
- [tex]\( P(X_i) \)[/tex] represents the probability associated with [tex]\( X_i \)[/tex].

We are given the following probabilities and corresponding hours studied:

\begin{tabular}{|c|c|}
\hline
Hours Studied ([tex]\(X_i\)[/tex]) & Probability ([tex]\(P(X_i)\)[/tex]) \\
\hline
0.5 & 0.07 \\
\hline
1 & 0.2 \\
\hline
1.5 & 0.46 \\
\hline
2 & 0.2 \\
\hline
2.5 & 0.07 \\
\hline
\end{tabular}

Now we can multiply each number of hours studied by its corresponding probability and sum the results:

[tex]\[ E(X) = (0.5 \times 0.07) + (1 \times 0.2) + (1.5 \times 0.46) + (2 \times 0.2) + (2.5 \times 0.07) \][/tex]

Calculating each term individually:

[tex]\[ 0.5 \times 0.07 = 0.035 \\ 1 \times 0.2 = 0.2 \\ 1.5 \times 0.46 = 0.69 \\ 2 \times 0.2 = 0.4 \\ 2.5 \times 0.07 = 0.175 \][/tex]

Now, sum these products together to find the mean:

[tex]\[ E(X) = 0.035 + 0.2 + 0.69 + 0.4 + 0.175 = 1.5 \][/tex]

Therefore, the mean of the probability distribution is:

[tex]\[ \boxed{1.5} \][/tex]