Question

Use your dice and cards reference sheets to help you answer the following questions. Given that a card dealer hands you a spade, what is the probability that it is the Jack of Spades?

A. 1/52
B. 1/13
C. 1/4
D. 1/12

Answer 1

The correct answer is B) 1/13.

P(Jack of spades given spades) = P(J|spades) = P(spades and J)/P(spades)

There is 1 Jack of spades out of 52 cards; P(spades and J) = 1/52
There are 13 spades out of 52 cards; P(spades) = 13/52 = 1/4

1/52 ÷ 1/4 = 1/52 × 4/1 = 4/52 = 1/13