Practice Problems (Junior Cert Mathematics): Flashcards

Events where one outcome doesn't affect another

Multiply probabilities when both independent events must happen

Add probabilities when either event can happen

Putting item back so total & probabilities stay same

$\frac{1}{2} \times \frac{1}{2} = \frac{1}{4}$

$1 - P(\text{both tails}) = 1 - \frac{1}{4} = \frac{3}{4}$

$\frac{1}{6} \times \frac{1}{6} = \frac{1}{36}$

4 aces

$\frac{4}{52} = \frac{1}{13}$

26 cards (hearts & diamonds)

$2, 4, 6$ so P(even) = $\frac{3}{6} = \frac{1}{2}$

Subtract probability from 1