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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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Kris V. | Experienced Mathematics, Physics, and Chemistry TutorExperienced Mathematics, Physics, and Ch...
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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


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.
Don L. | Fifteen years teaching and tutoring basic math skills and algebraFifteen years teaching and tutoring basi...
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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.