Question

A card is drawn at random from a pack of 52 cards. What is the probability that the card drawn is a spade or a king?

Options

• `1/13`

• `2/13`

• `4/13`

• `9/13`

Answer 1

`bb(4/13)`

Explanation:

A standard deck has 52 cards. 

Since we need the probability of drawing a spade or a king, we use:

P(A∪B) = P(A) + P(B) − P(A∩B)

where:

• P(A) = Probability of drawing a spade = `13/52`
• P(B) = Probability of drawing a king = `4/52`
• P(A∩B) = Probability of drawing the King of Spades (counted twice) = `1/52`

P(Spade or King) = `13/52 + 4/52 - 1/52`

= `16/52 = 4/13`