Question

Which of the following table of ordered pairs represents an exponential decay function?


x y
1 2
2 4
3 6
4 8
5 10

x y
1 2
2 4
3 8
4 16
5 32

x y
1 -2
2 -4
3 -6
4 -8
5 -10

x y
1 0.50
2 0.25
3 0.13
4 0.06
5 0.03

Answer 1

The fourth table:

x: 1 2 3 4 5
y: 0.50 0.25 0.13 0.06 0.03

Reason: each y-value is about half the previous one (0.50 → 0.25 → 0.125 ≈ 0.13 → 0.0625 ≈ 0.06 → 0.03125 ≈ 0.03), so the ratio between successive y's is ≈ 0.5 (a constant < 1), which is the hallmark of exponential decay. The others are either linear (first and third) or exponential growth (second).