To find the total fractional amount of the desired funds raised, we can add the two fractions together: \( \frac{3}{8} \) from the bake sale and \( \frac{1}{4} \) from the yard sale.
First, we need to make sure both fractions have a common denominator. The least common denominator (LCD) of 8 and 4 is 8.
Now, we can convert \( \frac{1}{4} \) to have a denominator of 8:
\[ \frac{1}{4} = \frac{1 \times 2}{4 \times 2} = \frac{2}{8} \]
Now we can add the two fractions:
\[ \frac{3}{8} + \frac{2}{8} = \frac{3 + 2}{8} = \frac{5}{8} \]
Therefore, the total fractional amount of the desired funds they have raised is \( \frac{5}{8} \).