To find the 24th percentile (\(P_{24}\)) of a given dataset, we need to follow these steps:
- Combine all the data values into a single sorted list.
- Calculate the index for the 24th percentile using the formula \( \text{index} = \frac{24}{100} \times (N + 1) \), where \(N\) is the total number of data points.
- If the index is an integer, the value at that index is the 24th percentile. If the index is not an integer, interpolate between the two closest data points.
First, we combine all the data values into a single list and sort them in ascending order:
\[
\text{data} = [1200, 1400, 1600, 1900, 2600, 2700, 3000, 3100, 4600, 4700, 4900, 5100, 5300, 5400, 5500, 5900, 6000, 6100, 6200, 6500, 6700, 6800, 6900, 7300, 7400, 7800, 8100, 8400, 8500, 8600, 8700]
\]
The formula to calculate the index for the 24th percentile is:
\[
\text{index} = \frac{24}{100} \times (N + 1)
\]
where \(N\) is the total number of data points. Given \(N = 31\):
\[
\text{index} = 0.24 \times (31 + 1) = 0.24 \times 32 = 7.68
\]
Since the index \(7.68\) is not an integer, we need to interpolate between the 7th and 8th data points. The 7th data point is \(3000\) and the 8th data point is \(3100\). The fractional part of the index is \(0.68\):
\[
P_{24} = 3000 + 0.68 \times (3100 - 3000) = 3000 + 0.68 \times 100 = 3000 + 68 = 3068
\]