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 calculate the mean of the probability distribution, we use the formula for the expected value of a discrete random variable [tex]\(X\)[/tex]:

[tex]\[ E(X) = \sum_{i} x_i \cdot P(x_i) \][/tex]

Where:
- [tex]\( x_i \)[/tex] are the values of the random variable [tex]\(X\)[/tex] (hours studied in this case).
- [tex]\( P(x_i) \)[/tex] are the corresponding probabilities for each value [tex]\( x_i \)[/tex].

Given the probability distribution:

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

We can find the mean of this distribution by calculating the weighted average of these values.

Step-by-step, the calculation is as follows:

1. Multiply each value of [tex]\(X\)[/tex] by its corresponding probability:

[tex]\[ \begin{align*} 0.5 \times 0.07 &= 0.035 \\ 1 \times 0.2 &= 0.2 \\ 1.5 \times 0.46 &= 0.69 \\ 2 \times 0.2 &= 0.4 \\ 2.5 \times 0.07 &= 0.175 \\ \end{align*} \][/tex]

2. Add these products together to get the expected value [tex]\(E(X)\)[/tex]:

[tex]\[ 0.035 + 0.2 + 0.69 + 0.4 + 0.175 = 1.5 \][/tex]

Therefore, the mean of the probability distribution is:

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