Question

Exponential Functions

Answer 1

You can use y2 - y1 / x2 - x1 to get the average rate of change

y2 is 21 and y1 is 18

x2 is 18 and x1 is 9

(21 - 18) / (18 - 9)

3 / 9

1/3

The depth is increasing at a rate of 1/3 per hour.

This written as a decimal rounded to the nearest tenth is:

0.3 feet per hour

Answer 2

At hour 9 the river is 18 feet deep.

At hour 18 the river is 21 feet deep.

From 9 to 18 hours is 9 hours difference.

From 18 to 21 feet is a 3 foot difference.

The average rate of change is the change in depth divided by the change in time:

3 feet / 9 hours = 0.3 feet per hour. ( Rounded to the nearest tenth)