Question

A population of cheetahs decreases 40% each year. What is the decay factor b in this situation?

Answer 1

Use this equation y = a (1 - b)^x

Where a is the initial population and b is the decay factor: 40/100 = 0.4

Therefore, the answer is that the decay factor b is 0.4.

This table shows some figures using the decay factor.

year     decrease      population

0         0                    a(1 - 0.4)^0 = a

1         a*0.4              a (1 - 0.4)^1 = a*0.6 = 0.6a

2        0.6a*0.4         a(1 - 0.4)^2 = a(0.6)^2 = 0.36a

3        0.36a*0.4        a(1 -0.4)^3= a(0.6)^3 = 0.216a