Mr. Whittaker’s science class uses tide gauges to measure annual variations in water levels at different parts of a river, and then compares those variations to the average annual trend.

Question

Matea recorded that the water level in one part of the river fell 1.05 millimeters per year for 2.48 years.

This data will be compared to the average annual trend, which shows the water level rising 1.8 mm/year.

Which number represents the rate at which the water level fell?

-1.05 mm/year
Which number should the rate be multiplied by to find the total variation in water level?

Answer 1

To find the total variation in water level, you can multiply the rate at which the water level fell by the number of years over which that fall occurred. In this case, the rate is -1.05 mm/year (indicating a fall in water level), and the time period is 2.48 years.

To find the total variation:

Total variation = Rate × Time Total variation = -1.05 mm/year × 2.48 years

So, the number you should multiply the rate by to find the total variation in water level is 2.48 years.