It would take 7.9 years to increase their population to 60.
An exponential function is in the form:
y = abˣ
where a is the initial value of y and b is the multiplier.
Let y represent the number of giraffes after x years.
From the question:
a = 20, b = 2, hence
[tex]y=20(2)^\frac{x}{5} \\\\for\ x=2:\\\\y=20(2)^\frac{2}{5} =26\\\\For\ y=60:\\\\60=20(2)^\frac{x}{5} \\\\2^\frac{x}{5} =3\\\\x=7.9\ years[/tex]
It would take 7.9 years to increase their population to 60.
Find out more on exponential function at: https://brainly.com/question/2456547