If each of the four friends swims \( \frac{3}{5} \) of a mile, you can find the total distance they swim by multiplying the distance each person swims by the number of friends.
Total distance = Distance per person × Number of friends
Total distance = \( \frac{3}{5} \text{ miles} \times 4 \)
Now, calculate:
\[ \frac{3}{5} \times 4 = \frac{3 \times 4}{5} = \frac{12}{5} = 2.4 \text{ miles} \]
So, the total distance they swim is 2.4 miles.