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Question

Keith applies a new brand of fertilizer to his grass.

He finds that the rate at which the grass grows can be modeled by a linear function.

He observes that the rate of growth is 1 centimeter every 3 days.

After 18 days, he measures the height of the grass to be 8 centimeters.

The initial height of the grass was
centimeters tall.

Answer 1

To find the initial height of the grass, we can use the information given about the rate of growth and the height after 18 days.

1. The grass grows at a rate of 1 centimeter every 3 days.

2. In 18 days, the grass will have grown:
   \[ \text{Growth} = \frac{18 \text{ days}}{3 \text{ days/cm}} = 6 \text{ cm} \]

3. The height after 18 days is 8 centimeters. Therefore, the initial height can be calculated as follows: \[ \text{Initial height} = \text{Height after 18 days} - \text{Growth} = 8 \text{ cm} - 6 \text{ cm} = 2 \text{ cm} \]

Thus, the initial height of the grass was 2 centimeters tall.