Initial Amount: 240 Rate of Growth: 25 % Value When t=3: ≈ 101.3
Practice makes perfect
Let's start by recalling the general formulas for exponential growth and exponential decay functions.
cc
Exponential Growth & Exponential Decay [0.8em]
y=a(1+r)^t & y=a(1-r)^t
In both cases, a>0 is the initial amount and r>0 is the rate of growth or decay written in decimal form. Moreover, for exponential decay r is less than 1. Let's rewrite the given function to match one of the above formulas.
Our function represents exponential decay, with an initial amount a= 240 and a rate of decay r= 0.25. To rewrite the rate of decay as a percent, we move the decimal point 2 places to the right.
r=0.25 ⇔ r=25 %
Finally, to evaluate the function when t=3 we will substitute 3 for t in the given formula.
