Probability

Probability = \frac{# of outcomes i the event}{# of possible outcomes}

  • range -> 0 – 1
  • the outcome will never happen – the outcome will always happen

Independent events: the outcome of the first eventĀ does not affect the outcome of the second event

  • Example -> rolling a dice, drawing a card from a stack and replacing H before drawing again
  • P(A and B) = P(A)P(B)
  • P(A or B) = P(A) + P(B)

You have the following 5 cards -> [2] [4] [6] [8] [10]

total outcomes = 5

P(6)=\frac{1}{5}

P(multiple of 4)=\frac{2}{5}

Draw 2 cards and replace each time

P(2 and 8) =P(2)p(8) = \frac{1}{5} \cdot \frac{1}{5}  = \frac{1}{25}

P(2 or 8) = p(2) +p(8) = \frac{1}{5} + \frac{1}{5} = \frac{2}{5}