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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?

For the Praxis Core exam
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2 Answers

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

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This answers my question and I also discovered the solution in a Khan Academy video. Will keep posting questions throughout the week.
Just saying thank you for your help. I passed all three of my Praxis exams and received the required score on the math. I am an older adult who is transitioning into a second career. I hadn't taken a math exam since graduate school and was never strong in math. Much appreciation for your help.
You are welcome.  Good luck with your future plan.
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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