Question

christian recorded the grade - level and instrument of everyone in the middle school school of rock below.
seventh grade students

instrument	# of students
bass	4
drums	7
keyboard	2

eighth grade students

instrument	# of students
bass	15
drums	13
keyboard	6

based on these results, express the probability that a student chosen at random will play the bass as a fraction in simplest form.
answer attempt 1 out of 2

Explanation:

Step1: Calculate total seventh - grade students

To find the total number of seventh - grade students, we sum up the number of students for each instrument in the seventh - grade table. The number of students for guitar is 6, bass is 4, drums is 7, and keyboard is 2. So the total number of seventh - grade students is $6 + 4+7 + 2=19$.

Step2: Calculate total eighth - grade students

For the eighth - grade table, the number of students for guitar is 4, bass is 15, drums is 13, and keyboard is 6. So the total number of eighth - grade students is $4 + 15+13 + 6 = 38$.

Step3: Calculate total number of students

To find the total number of students in both grades, we add the total number of seventh - grade students and eighth - grade students. So total students $=19 + 38=57$.

Step4: Calculate number of bass - playing students

The number of seventh - grade students who play bass is 4, and the number of eighth - grade students who play bass is 15. So the total number of students who play bass is $4 + 15 = 19$.

Step5: Calculate the probability

The probability of choosing a student who plays bass is the number of bass - playing students divided by the total number of students. So the probability is $\frac{19}{57}$. We can simplify this fraction by dividing both the numerator and the denominator by 19. $\frac{19\div19}{57\div19}=\frac{1}{3}$.

Answer:

$\frac{1}{3}$