To calculate the probability that an eighth grader chosen at random plays the drums, we first need to determine the total number of eighth graders and the number of eighth graders who play the drums.
From the data provided:
Eighth Grade Students:
- Guitar: 2
- Bass: 15
- Drums: 2
- Keyboard: 11
Now, let's calculate the total number of eighth graders: \[ \text{Total Eighth Graders} = 2 + 15 + 2 + 11 = 30 \]
Next, we note that the number of eighth graders who play the drums: \[ \text{Eighth Graders Playing Drums} = 2 \]
Now, we can calculate the probability that an eighth grader chosen at random plays the drums: \[ \text{Probability} = \frac{\text{Number of Eighth Graders Playing Drums}}{\text{Total Eighth Graders}} = \frac{2}{30} \]
To express this probability as a percentage, we multiply by 100: \[ \text{Probability as a Percent} = \left( \frac{2}{30} \right) \times 100 = \frac{200}{30} \approx 6.67% \]
Rounding to the nearest whole number gives us: \[ \text{Probability as a Percent} \approx 7% \]
Therefore, the probability that an eighth grader chosen at random will play the drums is \( \boxed{7} \) percent.