Answer:
13/35
Explanation:
Probability determines the likelihood of an event happening.
Since we are not looking at the 7th Graders list, let's focus on the list on 8th Graders.
Given:
Guitar - 4 students
Bass - 13 students
Drums - 13 students
Keyboard - 5 students
Since we are trying to find the probability of an eighth grader chosen at random to play the drums, let's turn our attention to how many students actually play the drums.
13 students play the drums.
In order to find the probability of a student chosen at random who plays the drums, we have to find how many students play the drums (which we already found) out of the total amount of students there are in that grade/section. Summing up, probability = the amount of favorable cases divided by the amount of possible cases.
Let's use this formula:
P(A) = n/N
Where "P(A)" stands for the probability of the event "A". And "n" represents the # of favorable outcomes and "N" represents the # of total possible outcomes.
Let's find how many students are in 8th grade now by adding all the people who play the musical instruments together:
4 + 13 + 13 + 5
= 35 possible outcomes.
Now let's plug it into the formula:
P(A) = n/N
P(A) = 13/35
13/35 can simplify any further.
The probability of choosing a student who plays the drums at random is 13/35.