Question

A species of dolphins is decreasing at a rate of 3.1% per year. If there are currently 20,000 dolphins, how many will there be in 30 years?

Answer 1

Answer:

About 7,776 dolphins

Step-by-step explanation:

we know that

The equation of a exponential decay function is given by

$y=a(1-r)^x$

where

y is the number of species of dolphins

x is the number of years

a is the initial value

r is the rate of change

we have

$a=20,000\\r=3.1\%=3.1/100=0.031$

substitute

$y=20,000(1-0.031)^x$

$y=20,000(0.969)^x$

How many dolphins will there be in 30 years?

For x=30 years

substitute in the equation

$y=20,000(0.969)^{30}=7,776$