Answer: The answer is 0.25 miles.
Step-by-step explanation: Given that my friend started walking at a speed of 3 miles per hour and I started 5 minutes after him at a speed of 4 miles per hour. We need to find the number of miles my friend travelled when I started walking.
Since I started 5 minutes after than my friend, so we are to find the distance travelled by my friend in 5 minutes.
In 1 hour, i.e., 60 minutes, distance travelled by my friend = 3 miles.
In 1 minute, distance travelled by my friend is
Therefore, distance travelled by my friend in 5 minutes will be
Thus, the answer is 0.25 miles.