Sung-Hi is filling a sandbox with sand at the rate shown in the table below. Which statement must be true regarding the linear function that represents this situation?

Amount of Sand in the Sandbox

Number of Minutes Since Sung-Hi Started

0

1

2

3

4

Amount of Sand in the Sandbox (pounds)

200

220

240

260

280

The initial value must be 0 pounds.

The initial value must be 20 pounds.

The rate of change must be 0 pounds per minute.

The rate of change must be 20 pounds per minute.

The initial value is the amount of sand in the sandbox at 0 minute. Given the table, we can see that the initial value is 200. So the first two choices are incorrect.

Let's find the rate of change. Rate of change is the difference in the amount of sand each minute passed. Based on the table we can see that the difference in the amount of sand from 0 minute to 1 minute is 220 - 200 = 20 pounds. That difference is the same for every next minute passed. So the rate of change is 20 pounds.

The answer choice is D.