Question

The table below shows the saturated thickness (water level) in five-year intervals.


Water Levels in the Ogallala Aquifer

mc026-1.jpg

If water continues to be used at the current rate, what will the saturated thickness be in 2020?
8–10 meters
10–12 meters
14–16 meters
18–20 meters

Answer 1

I can't see the image file you referenced. Could you either type the table values (years and thicknesses) or upload the picture again?

If you want to do it yourself, here are the steps to extrapolate to 2020:

1. Pick two points from the table (year, thickness). Preferably the earliest and latest available.
2. Compute the rate of change (slope) in meters per year:
slope = (thickness2 − thickness1) / (year2 − year1).
3. Find how many years from your latest data point to 2020, then add (slope × number of years) to the latest thickness to get the predicted 2020 thickness.
4. Choose the answer choice that contains that predicted value.

Example: if the table shows 2000 → 16 m and 2010 → 14 m, slope = (14−16)/(2010−2000) = −2/10 = −0.2 m/yr. From 2010 to 2020 is 10 years, predicted change = −0.2×10 = −2, so 2010 thickness 14 − 2 = 12 m → choose 10–12 meters.

Send the table values and I’ll compute the exact answer.