Answer:
9/23
Explanation:
Of the 23 students, 9 play both baseball and basketball. The probability of choosing one of those is 9/23.
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Let A represent basketball, and B represent baseball. Then ...
P(A or B) = P(A) +P(B) -P(A and B)
Since 8 students play neither sport, we have ...
1 -8/23 = 11/23 +13/23 -P(A and B)
15/23 = 24/23 -P(A and B)
P(A and B) = (24 -15)/23
P(A and B) = 9/23