Question

At 4 PM, the level of the water in the lake was 10 feet. At 8 PM, the level of the water was 2 feet. Determine the constant rate of change of the water.

Answer 1

`-4\ \text{feet/hour}`

Explanation:

Level of water at 4 PM is 10 feet.

Level of water at 8 PM is 2 feet.

Time duration in which water level is measured is
`8-4=4\ \text{hours}`

The change of the level of water in the given time duration is
`2-10=-8\ \text{feet}`

The rate of change would be

`R=(-8)/(4)=-4\ \text{feet/hour}`

The constant rate of change of the water is
`-4\ \text{feet/hour}`.

The minus sign indicates that the water level is reducing.