One card is selected from a standard deck of 52 playing cards. What is the probability that the card is either a spade or a four?

Question

For the Praxis Core exam

Answer 1

P{a spade or a four} =  P{a spade} + P{a four} - P{a spade and a four}

                               = 13/52+ 4/52 - 1/52

                               = 16/52

                               = 4/13

Answer 2

Hi Miss, to find the probability of the card being either a space or a four, start by find the probability of getting a spade. Then, find the probability of getting a four. Last, add the two probabilities to get the final probability.

 

P(a spade) = 13/52, or 1/4, since there are 13 spades in a standard deck.

 

p(a four) = 4/52, or 1/13, since there are 4 fours in a standard deck.

 

p(a spade or a four) = 1/4 + 1/13, which is equal to: 13/52 + 4/52 = 17/52

 

Note: the common denominator for 4 and 13 is 52, we could have eliminated the steps to reduce both fractions.

 

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