Flashcard 15 - Mathematics Knowledge Flashcard Set for the ASVAB

\[\frac{9}{10}\]

The rules for addition/subtraction and multiplication of fractions and the concept of lowest common denominator (LCD) were used in solving this problem.

If \(\frac{1}{5}\) of the group left, then \(\frac{4}{5}\) of the group was left.

\[1 - \frac{1}{5} = \frac{4}{5}\]

Then, if \(\frac{1}{2}\) of the \(\frac{1}{5}\) who left returned:

\[\frac{1}{2} \cdot \frac{1}{5} = \frac{1}{10}\]

So, add \(\frac{1}{10}\) to the \(\frac{4}{5}\) remaining at the meeting:

\[\frac{4}{5} + \frac{1}{10}\]

Find a common denominator in order to add fractions:

\[\frac{4}{5} \cdot \frac{2}{2} = \frac{8}{10}\]

So:

\[\frac{8}{10} + \frac{1}{10} = \frac{9}{10}\]