Question 1123858
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With 12 candidates, there are  {{{C[12]^4}}} = {{{(12*11*10*9)/(1*2*3*4)}}} = 495  ways to form different groups of 4 persons.


With 6 Democrats, there are  {{{C[6]^4}}} = {{{(6*5*4*3)/(1*2*3*4)}}} = 15  ways to form different groups of 4 persons.


The probability under the question is the ratio of these two numbers, i.e.  {{{15/495}}} = {{{1/33}}} = 0.03030 = 3.03%.
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Solved.