Some Argue That Millions of Americans Are So Hooked on Television

Multiple Choice

Some argue that millions of Americans are so hooked on television that their viewing habits fit the criteria for substance abuse, as defined in the official psychiatric manual. Choose a young person (age 19 to 25) at random and ask, "In the past seven days, how many days did you watch television?" Call the response X for short. Here is a probability model for the response:
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$$\begin{array} { | l | l | l | l | l | l | l | l | l | } \hline \text { Days } X & 0 & 1 & 2 & 3 & 4 & 5 & 6 & 7 \\\hline \text { Probability } & 0.04 & 0.03 & 0.06 & 0.08 & 0.09 & 0.08 & 0.05 & ? \\\hline\end{array}$$ This is a legitimate probability model. Therefore, what is the value of P(X = 7) ?

A) 1/7
B) 1/8
C) 0.43
D) 0.57