A die is rolled. What is the probability of rolling a 5 or a number greater than3

解

A d i e i s ro ll e d . Wha t i s t h e p ro babi l i t y o f ro ll in g a 5 or a n u mb er g re a t er t han 3

\frac{1}{2}

十進法表記

0.5

解答ステップ

Find the probability of rolling a 5:

\frac{1}{6}

Find the probability of a number greater than 3:

\frac{1}{2}

Find the probability of rolling a 5 and a number greater than 3:

\frac{1}{6}

Use the Inclusion-Exclusion formula

P (X \lor Y) = P (X) + P (Y) - P (X \land Y)

= \frac{1}{6} + \frac{1}{2} - \frac{1}{6}

類似した元を足す:

\frac{1}{6} - \frac{1}{6} = 0

= \frac{1}{2}