At 1:00 pm the water level in a pool is 13 inches. At 1:30pm the water level is 18 inches. At 2:30pm the water level is 28 inches. What is the constant rate of change?

From the given question we come to know of certain number of facts and they are:

At 1:00 PM the water level of the pond was = 13 inches

At 1:30 PM the water level of the pond was = 18 inches

At 2:30 PM the water level of the pond was = 28 inches

From the above given facts we can easily find the amount of water changing every half an hour.

Amount of increase in water from 1:00PM to 1:30 PM = (18 - 13) inches

= 5 inches

Amount of increase in water level from 1:30PM to 2:30PM = (28 - 18) inches

= 10 inches

From the above two deductions we can come to the conclusion the the constant rate of change in water level is 5 inches for every half an hour.

Per 1/2 an hour it is changes by 5 so the constant rate would be: 5 inches per 1/2 an hour