Let x = time, hours, from 1:00
Let y = water level, inches
Note that from 1:00 to 2:30, x = 2.5 - 1.0 = 1.5 hours.
The given data is
x: 0 1.5
y: 13 28.0
The change in x is 1.5 - 0 = 1.5 hours
he change in y is 28 - 13 = 15 inches
The rate of change is (15 inches)/(1.5 hours) = 10 inches/hour
Answer: 10 inches per hour
