To find Jacob's unit rate in miles per minute, we need to determine how many miles he skates in one minute.
He skates \( \frac{3}{10} \) of a mile in \( \frac{1}{2} \) minute. To find his rate in miles per minute, we can set up the calculation as follows:
- Determine how many times \( \frac{1}{2} \) minute fits into 1 minute:
\[ 1 \text{ minute} \div \frac{1}{2} \text{ minute} = 2 \]
- Since he skates \( \frac{3}{10} \) of a mile in \( \frac{1}{2} \) minute, in 1 minute he will skate:
\[ 2 \times \frac{3}{10} = \frac{6}{10} = \frac{3}{5} \text{ miles} \]
Thus, Jacob's unit rate is \( \frac{3}{5} \) miles per minute.
The correct answer is:
A. \( \frac{3}{5} \)