A city council consists of eight Democrats and eight Republicans. If a committee of six people is selected, find the probability of selecting two Democrats and four Republicans.

(Type answer a fraction Simplify your answer.)

Respuesta :

Answer:

The  probability is  [tex]P[ D n R] = 0.196[/tex]

Step-by-step explanation:

  From the question we are told that

     The number of Democrats is  [tex]D = 8[/tex]

       The number of republicans is  [tex]R = 8[/tex]

The  number of ways of selecting selecting two Democrats and four Republicans.

         [tex]N = \left {D} \atop {}} \right. C_2 * \left {R} \atop {}} \right. C_1[/tex]

Where C represents combination

substituting values

           [tex]N = \left {8} \atop {}} \right. C_2 * \left {8} \atop {}} \right. C_1[/tex]

           [tex]N = \left {8} \atop {}} \right. C_2 * \left {8} \atop {}} \right. C_1 = \frac{8!}{(8-2)! 2!} * \frac{8! }{(8-4)! 1 !}[/tex]

=>        [tex]N = \left {8} \atop {}} \right. C_2 * \left {8} \atop {}} \right. C_1 = \frac{8!}{(6)! 2!} * \frac{8! }{(6)! 1 !}[/tex]

=>        [tex]N = \left {8} \atop {}} \right. C_2 * \left {8} \atop {}} \right. C_1 = \frac{8 * 7 * 6!}{(6)! 2!} * \frac{8*7 *6! }{(6)! 1 !}[/tex]

=>        [tex]N = \left {8} \atop {}} \right. C_2 * \left {8} \atop {}} \right. C_1 = \frac{8 * 7 }{ 2*1 } * \frac{8*7 }{ 1 *1 }[/tex]

=>      [tex]N = 1568[/tex]

The total number of ways of selecting the committee of six people is  

          [tex]Z = \left {D+R} \atop {}} \right. C_6[/tex]

substituting values

           [tex]Z = \left {8+8} \atop {}} \right. C_6[/tex]

            [tex]Z= \left {16} \atop {}} \right. C_6[/tex]

substituting values

             [tex]Z= \left {16} \atop {}} \right. C_6 = \frac{16! }{(16-6) ! 6!}[/tex]

           [tex]Z= \left {16} \atop {}} \right. C_6 = \frac{16 *15 *14 * 13 * 12 * 11 * 10! }{10 ! 6!}[/tex]

           [tex]Z= \left {16} \atop {}} \right. C_6 = \frac{16 *15 *14 * 13 * 12 * 11 }{6* 5 * 4 * 3 * 2 * 1}[/tex]

           [tex]Z= \left {16} \atop {}} \right. C_6 = 8008[/tex]

The probability of selecting two Democrats and four Republicans  is  mathematically  represented as

           [tex]P[ D n R] = \frac{N}{Z}[/tex]

substituting values

           [tex]P[ D n R] = \frac{1568}{8008}[/tex]

            [tex]P[ D n R] = 0.196[/tex]

   

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