document.write( "Question 1130879: What type of problem is this and how do I solve it?\r
\n" ); document.write( "\n" ); document.write( "If 15 of the students from the special programs are randomly selected, find the probability that 12 of them graduated (84% for students admitted through special programs).
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Algebra.Com's Answer #747538 by Theo(13342)\"\" \"About 
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15 students from the special program are selected.
\n" ); document.write( "84.
\n" ); document.write( "the probability that a student from the special program graduates is 84% = .84
\n" ); document.write( "you want to find the probability that 12 of them graduated.\r
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\n" ); document.write( "\n" ); document.write( "looks like a binomial probability type problem.\r
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\n" ); document.write( "\n" ); document.write( "equation for that is p(x) = p^x * q^(n-x) * c(n,x)\r
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\n" ); document.write( "\n" ); document.write( "in this problem, that becomes:\r
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\n" ); document.write( "\n" ); document.write( "p(12) = .84 ^ 12 * (1 - .84) ^ 15 - 12) * c(15,12)\r
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\n" ); document.write( "\n" ); document.write( ".84 is the probability that a student from the special program will graduate.
\n" ); document.write( "1 - .84 = .16 is the probability that a student from the special program will not graduate.
\n" ); document.write( "c(15,12) = the number of ways you can get a set of 12 elements from a set of 15 elements = 15! / (12! * 3!) = 455\r
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\n" ); document.write( "\n" ); document.write( "the formula becomes .84 ^ 12 * .16 ^ 3 * 455 = .229997321.\r
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\n" ); document.write( "\n" ); document.write( "i checked out all the probabilities using excel.
\n" ); document.write( "the total probability is 1 as it should be.
\n" ); document.write( "here's a display of what excel showed me.\r
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\n" ); document.write( "\n" ); document.write( "look at the row where x = 12 and you'll see that p(x) equals 0.229997321 which is the same as i got manually using my scientific calculator.\r
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\n" ); document.write( "\n" ); document.write( "that is the probability that exactly 12 of them graduated if you picked those 12 out of 15 randomly selected student in the special program.\r
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