Concept:
For a moderately skewed frequency distribution, the empirical relation between mean, median, and mode is:
\[
\text{Mode} = 3(\text{Median}) - 2(\text{Mean})
\]
This relation is commonly used in statistics when direct calculation of mode is difficult.
Step 1: Write the given values.
Given:
\[
\text{Mean} = 21
\]
\[
\text{Median} = 22
\]
We need to find:
\[
\text{Mode}
\]
Step 2: Use the empirical formula.
\[
\text{Mode}
=
3(\text{Median})
-
2(\text{Mean})
\]
Substituting the values:
\[
\text{Mode}
=
3(22)
-
2(21)
\]
\[
=
66
-
42
\]
\[
=
24
\]
Thus,
\[
\boxed{\text{Mode} = 24.0}
\]
Hence, the correct option is:
\[
\boxed{(E)\ 24.0}
\]