Create a frequency table with cumulative frequency and sums for fi, fi Xi, and fi X_i2.

The cumulative frequency for each row is the sum of the frequencies up to that row.

Multiply each frequency ($f_i$) by its corresponding value ($X_i$).

Square each value ($X_i$).

Multiply each frequency ($f_i$) by its corresponding squared value ($X_i^2$).

Sum the values in the $f_i$, $f_i X_i$, and $f_i X_i^2$ columns.

The completed table is:

The required sums are:

• $\sum f_i = \boxed{\mathbf{30}}$
• $\sum f_i X_i = \boxed{\mathbf{90}}$
• $\sum f_i X_i^2 = \boxed{\mathbf{342}}$