document.write( "Question 789037: Ok tried this Three times and get figure out how to get the answer.\r
\n" ); document.write( "\n" ); document.write( "37% of all doctors are family practioners. If there are 5 doctors at a gathering, what is the probability that 3 of them are family practioners?\r
\n" ); document.write( "\n" ); document.write( "I am 53 years of age, out of school since the 70's - never had to do Formulas and am completely confused (I am back in college earning my Bachelors in Liberal Arts) I am failing Statistics because I do not understand it. Can someone PLEASE help? \n" ); document.write( "
Algebra.Com's Answer #478709 by rothauserc(4718)\"\" \"About 
You can put this solution on YOUR website!
let's say we have 100 doctors, then 37% of 100 gives us 37 doctors that are family practitioners
\n" ); document.write( "then we are told that at a gathering we have 5 doctors and to calculate the probability that 3 of them are family practitioners
\n" ); document.write( "now we use combinations to calculate the probability
\n" ); document.write( "we multiply the combination of 37 taken 3 at a time by the combination of 63 taken two at a time and then divide by the combination of 100 taken 5 at a time
\n" ); document.write( "the combination of 37 taken 3 at a time = 37! / (3! * (37-3)!) = 7770
\n" ); document.write( "the combination of 63 taken two at a time = 1953
\n" ); document.write( "the combination of 100 taken 5 at a time = 7.528752e7
\n" ); document.write( "now we can calculate
\n" ); document.write( "(7770 * 1953) / 7.528752e7
\n" ); document.write( "1.517481e7 / 7.528752e7
\n" ); document.write( "0.20155810684161199625
\n" ); document.write( "this tells us that the probability that 3 doctors are family practitioners is 20%\r
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