An ordinary (fair) coin is tossed 3 times. Outcomes are thus triples of "heads" ( [tex]$h$[/tex] ) and "tails" ( [tex]$t$[/tex] ) which we write [tex]$h t h, t t t$[/tex], etc.

For each outcome, let [tex]$N$[/tex] be the random variable counting the number of tails in each outcome. For example, if the outcome is [tex]$t t h$[/tex], then [tex]$N(t t h)=2$[/tex]. Suppose that the random variable [tex]$X$[/tex] is defined in terms of [tex]$N$[/tex] as follows: [tex]$X=N^2-2N-3$[/tex]. The values of [tex]$X$[/tex] are given in the table below.

\begin{tabular}{|c|c|c|c|c|c|c|c|c|}
\hline Outcome & [tex]$t h h$[/tex] & [tex]$h h t$[/tex] & [tex]$t t h$[/tex] & [tex]$h t t$[/tex] & [tex]$h t h$[/tex] & [tex]$t t t$[/tex] & [tex]$h h h$[/tex] & [tex]$t h t$[/tex] \\
\hline Value of [tex]$X$[/tex] & -4 & -4 & -3 & -3 & -4 & 0 & -3 & -3 \\
\hline
\end{tabular}

Calculate the probabilities [tex]$P(X=x)$[/tex] of the probability distribution of [tex]$X$[/tex]. First, fill in the first row with the values of [tex]$X$[/tex]. Then fill in the appropriate probabilities in the second row.

\begin{tabular}{|c|c|c|c|}
\hline Value [tex]$x$[/tex] of [tex]$X$[/tex] & [tex]$\square$[/tex] & [tex]$\square$[/tex] & [tex]$\square$[/tex] \\
\hline [tex]$P(X=x)$[/tex] & [tex]$\square$[/tex] & [tex]$\square$[/tex] & [tex]$\square$[/tex] \\
\hline
\end{tabular}



Answer :

Alright, let's tackle this question step-by-step.

1. Identifying the unique values of [tex]\( X \)[/tex]

From the data given:
[tex]\[ \begin{tabular}{|c|c|c|c|c|c|c|c|c|} \hline Outcome & t h h & h h t & t t h & h t t & h t h & t t t & h h h & t h t \\ \hline Value of $X$ & -4 & -4 & -3 & -3 & -4 & 0 & -3 & -3 \\ \hline \end{tabular} \][/tex]

The unique values of [tex]\( X \)[/tex] are [tex]\( -4 \)[/tex], [tex]\( -3 \)[/tex], and [tex]\( 0 \)[/tex].

2. Counting the occurrences for each value of [tex]\( X \)[/tex]

- For [tex]\( X = -4 \)[/tex]: The outcomes where [tex]\( X = -4 \)[/tex] are [tex]\( t h h \)[/tex], [tex]\( h h t \)[/tex], and [tex]\( h t h \)[/tex]. Hence, the count is [tex]\( 3 \)[/tex].
- For [tex]\( X = -3 \)[/tex]: The outcomes where [tex]\( X = -3 \)[/tex] are [tex]\( t t h \)[/tex], [tex]\( h t t \)[/tex], [tex]\( h h h \)[/tex], and [tex]\( t h t \)[/tex]. Hence, the count is [tex]\( 4 \)[/tex].
- For [tex]\( X = 0 \)[/tex]: The outcome where [tex]\( X = 0 \)[/tex] is [tex]\( t t t \)[/tex]. Hence, the count is [tex]\( 1 \)[/tex].

3. Calculating the probabilities

We have a total of [tex]\( 8 \)[/tex] possible outcomes (since a fair coin is tossed [tex]\( 3 \)[/tex] times, [tex]\( 2^3 = 8 \)[/tex]).

Now, we calculate the probabilities [tex]\( P(X=x) \)[/tex] as follows:
- [tex]\( P(X = -4) = \frac{3}{8} = 0.375 \)[/tex]
- [tex]\( P(X = -3) = \frac{4}{8} = 0.5 \)[/tex]
- [tex]\( P(X = 0) = \frac{1}{8} = 0.125 \)[/tex]

4. Filling in the table

Now, we can fill in these values into the table:

[tex]\[ \begin{tabular}{|c|c|c|c|} \hline Value $x$ of $X$ & -4 & -3 & 0 \\ \hline $P ( X = x )$ & 0.375 & 0.5 & 0.125 \\ \hline \end{tabular} \][/tex]

This completes our detailed solution.