Respuesta :
There are 6 teachers and 15 students to choose from
To form a committee of 5 teachers and 4 students
The combination rule will be applied
From 6 teachers, The number of ways 5 teachers can be selected is
[tex]^6C_5[/tex]From 15 students, the number of ways 4 students can be selected is
[tex]^{15}C_{4^{}}[/tex]Therefore, the total number of ways a committee of 5 teachers and 4 students can be formed from 6 teachers and 15 students is
[tex]^6C_5\times^{15}C_{4^{}}[/tex]Simplifying this gives
[tex]^6C_5\times^{15}C_{4^{}}=\frac{6!}{(6-5)!\times5!}\times\frac{15!}{(15-4)!\times4!}[/tex]This further gives
[tex]\begin{gathered} ^6C_5\times^{15}C_{4^{}}=\frac{6!}{1!\times5!}\times\frac{15!}{11!\times4!} \\ ^6C_5\times^{15}C_{4^{}}=\frac{6\times5!}{1\times5!}\times\frac{15\times14\times13\times12\times11!}{11!\times4\times3\times2\times1} \end{gathered}[/tex]Cancel out common factors
[tex]\begin{gathered} ^6C_5\times^{15}C_{4^{}}=6\times\frac{15\times14\times13\times12}{4\times3\times2\times1} \\ ^6C_5\times^{15}C_{4^{}}=6\times\frac{32760}{24} \\ ^6C_5\times^{15}C_{4^{}}=6\times1365 \\ ^6C_5\times^{15}C_{4^{}}=8190 \end{gathered}[/tex]Therefore, the number of ways the committee can be formed is 8190 ways
