Question

there were 200,00 animals of a certain species in 1980. since then, this number has decreased by 4.5% each year. approximately how many animals of this species will be left in 2025?

Answer 1

The number of animals of the species will be left in 2025 = 2519 animals

Explanation:

The number of animals of a certain species in 1980 = 20000

The rate of decrease each year = 4.5 %

The number of animals left in 2025 = ???

The number of years between 1980 and 2025 = 45

By formula of depreciation,

`Pn = P (1 - R/100) ^ T`

where Pn is the population in 2025

P is the population in 1980

R is the rate of decrease in population

Substituting the values in the equation, we get

`Pn = 20000 (1 - 4.5/100) ^ {45}`

=
`20000 (0.955) ^ {45}`

=2518.7 = 2519 species.