You are dealt one card from a standard 52-card deck. Find the probability of being dealt an ace or a 9. Enter your answer in a reduced fraction form.

解

Y o u a re d e a lt o n e c a r d f ro m a s t an d a r d 52 - c a r d d ec k . F in d t h e p ro babi l i t y o f b e in g d e a lt an a ce or a 9. E n t er yo u r an s w er in a re d u ce d f r a c t i o n f or m .

\frac{2}{13}

十進法表記

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解答ステップ

Find the probability of being dealt an ace:

\frac{1}{13}

Find the probability of a 9;.:

\frac{1}{13}

Since the events are disjoint, Use the formula

P (X_{1} \lor X_{2} \lor \dots \lor X_{k}) = P (X_{1}) + P (X_{2}) + \dots + P (X_{k})

= \frac{1}{13} + \frac{1}{13}

\frac{1}{13} + \frac{1}{13} = \frac{2}{13}

= \frac{2}{13}