Answer:
Left: The substance is decreasing by 1/2 every 12 years
Right: The substance is decreasing by 5.61% each year
Step-by-step explanation:
exponential decay
A = P(1-r)ᵇⁿ, where A is the final amount, P is the initial amount, r is the rate decreased each time period, b is the number of years, and n is the number of times compounded each year
let's write each formula in terms of this
left:
f(t) = 600(1/2)^(t/12)
matching values up...
A = P(1-r)ᵇⁿ
A = f(t)
P = 600
1 - r = 1/2 -> r = 1/2
t/12 = bn -> b = number of years = t, so bn = b/12 -> n = 1/12. Thus, it is compounded 1/12 times each year, so it is compounded every t*12 = 12 years. If it was compounded each month, it would be compounded 12 times a year
Thus, this is decreasing by a rate of 1/2 each 12 years
right:
f(t) = 600(1-0.0561)^(t)
matching values up...
A = P(1-r)ᵇⁿ
A = f(t)
P = 600
1 - r = 1 - 0.0561 -> r = 0.0561 = 5.61%
t = bn -> b = number of years = t, so bn = b -> n = 1. Thus, it is compounded annually (1 time each year)
Thus, this is decreasing by a rate of 5.61% each year
