Casho recorded the grade-level and instrument of everyone in the middle school School of Rock below.
Seventh Grade Students
Instrument # of Students
Guitar 5
Bass 10
Drums 13
Keyboard 13
Eighth Grade Students
Instrument # of Students
Guitar 9
Bass 10
Drums 10
Keyboard 4
Based on these results, express the probability that an eighth grader chosen at random will play an instrument other than drums as a fraction in simplest form.
First, we need to find the total number of eighth grade students who play an instrument other than drums. This can be found by adding the number of eighth grade students who play guitar, bass, and keyboard: 9 (guitar) + 10 (bass) + 4 (keyboard) = 23 students.
Next, we find the total number of eighth grade students: 9 (guitar) + 10 (bass) + 10 (drums) + 4 (keyboard) = 33 students.
Therefore, the probability that an eighth grader chosen at random will play an instrument other than drums is 23/33, which simplifies to 7/11.