Answer:
<h2> 3/11</h2>
Step-by-step explanation:
FORMULA= P(A)=
NUMBER OF FAVORABLE OUTCOMES
-------------------------------------------------------------
NUMBER OF POSSIBLE OUTCOMES
GIVEN: 12 Guitars, 10 Bass, 9 Drums, 12 Keyboards
WANT: The probality a seventh grader chosen at randome will play drums
add all the instruments
12+10+9+12=33
there are 9 drums
FOLLOW THE FORMULA
9 3
---- = ---- SIMPLIFIES FORM
33 11