Question 1157923
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I think saying the statement of the problem is incorrect is a bit harsh.  I do think that the problem is presented poorly.<br>
By implication, the problem really asks the probability if, WHEN 9 BOOKS ARE SELECTED FROM 9 science books and 10 math books, 4 science books and 5 math books are selected.<br>
P(4 science and 5 math) = {{{(C(9,4)*C(10,5))/C(19,9) = (126*252)/92378 = 31752/82378}}}<br>
Of course simplify the fraction or express as a decimal if needed.<br>