Answer
$2$ haircuts completed per hour
Work Step by Step
At 2 P.M., a total of 7 haircuts were completed.
By 4:30 P.M., a total of 12 haircuts were completed.
The increase in number of haircuts completed was:
$=12-7=5$
The elapsed time from 2 p.m.. to 4:30 p.m. is 2.5 hours.
Thus, the average rate is:
$=\dfrac{5\text{ haircuts completed}}{2.5 \text{ hours}}=2$ haircuts completed per hour
