To determine the numbers that contain the bottom 25% of the data, we need to calculate the first quartile (Q1) of the data set. This involves sorting the data and finding the value below which 25% of the data falls.
First, we sort the given data set in ascending order:
\[
\text{data} = [35, 50, 25, 30, 45, 40, 55, 60, 20, 65]
\]
\[
\text{sorted\_data} = [20, 25, 30, 35, 40, 45, 50, 55, 60, 65]
\]
Next, we calculate the first quartile (\(Q1\)), which is the value below which 25% of the data falls. For the sorted data, \(Q1\) is:
\[
Q1 = 31.25
\]
We then identify the values in the sorted data that are less than or equal to \(Q1\):
\[
\text{bottom\_25\_percent} = [20, 25, 30]
\]