According to a recent survey in 2000 58 of households had on

According to a recent survey, in 2000, 58% of households had one or more pets. Throughout the the next decade, this decreased by approximately 2% per year. Express the percentage of households having pets, P, as a function of the number of years after 2000, x.

Solution

exponential growth y = a . (1- r)^x

a = initial amount before measuring decay
r = growth/decay rate (often a percent)
x = number of time intervals that have passed

a = out of hundred 58 are having pets

r = 2% = 0.02

x = 1 year

P = 58 (1 -0.02)^1

= 56.84

so after one year 56.84% houses will have pets

P = 58 (1- 0.02)^x