Question

WILL MARK AS BRIANILIEST!
There are 25000 whale sharks on earth. they decrease 63% a year.
Write this into an exponential function.

Answer 1

Answer: $y(n)=0.37^n\cdot25000$

Steps:

A decrease of an amount x by 63% is the same as (x - x*0.63), or x*(1-0.63), or x*0.37.

The decrease is per year. So after one year the amount is 0.37*x, which then again decreases by 63%, so the amount after two years will be $0.37^2x$, and so on. And so after n years, the amount will be:

$y(n) = 0.37^nx$

Finally, we are given the amount x - the initial number of whale sharks 25000, so the final exponential function describing the whale shark count after n years:

$y(n)=0.37^n\cdot25000$