To find out how many 1/4 pound burgers Hannah can make from 9 1/2 pounds of ground beef, we first need to convert the mixed fraction into an improper fraction.
9 1/2 pounds can be converted as follows:
\[ 9 \times 2 + 1 = 19 \]
So, \(9 \frac{1}{2}\) pounds is equal to \(\frac{19}{2}\) pounds.
Next, we need to divide this amount by the weight of each burger, which is 1/4 pound. Dividing by a fraction is the same as multiplying by its reciprocal:
\[ \frac{19}{2} \div \frac{1}{4} = \frac{19}{2} \times \frac{4}{1} = \frac{19 \times 4}{2 \times 1} = \frac{76}{2} = 38 \]
Therefore, Hannah can make 38 quarter-pound burgers.