Step 1 :An ordinary (fair) coin is tossed 3 times. Outcomes are thus triples of "heads" (h) and "tails" (t) which we write h t h, t t t, etc.
Step 2 :For each outcome, let N be the random variable counting the number of heads in each outcome. For example, if the outcome is h t h, then N ( h th) =2. Suppose that the random variable X is defined in terms of N as follows: X=N-N^{2}-3. The values of X are given in the table below.
Step 3 :\begin{tabular}{|c|c|c|c|c|c|c|c|c|} \hline Outcome & h t h & h h t & t t t & t h t & h h h & h t t & t t h & t h h \\ \hline Value of X & -5 & -5 & -3 & -3 & -9 & -3 & -3 & -5 \\ \hline \end{tabular}
Step 4 :The first step is to calculate the total number of outcomes. Since we are tossing a coin 3 times, and each toss has 2 possible outcomes (heads or tails), the total number of outcomes is \(2^3 = 8\).
Step 5 :Next, we need to count the number of outcomes for each value of X. From the table, we can see that X can take on the values -9, -5, and -3.
Step 6 :The value of X is -9 for 1 outcome (h h h), -5 for 3 outcomes (h t h, h h t, t h h), and -3 for 4 outcomes (t t t, t h t, h t t, t t h).
Step 7 :The probability P(X=x) is then the number of outcomes for which X=x divided by the total number of outcomes.
Step 8 :\[P(X=-9) = \frac{1}{8} = \boxed{0.125}\]
Step 9 :\[P(X=-5) = \frac{3}{8} = \boxed{0.375}\]
Step 10 :\[P(X=-3) = \frac{4}{8} = \boxed{0.5}\]