It will take 18 minutes until the coffee is safe to drink.
Exponential function, as its name suggests, involves exponents. But note that, an exponential function has a constant as its base and a variable as its exponent but not the other way round.
Here, given equation
F(t) = F₂ + (F₁-F₂)[tex]e^{-kt}[/tex]
F₂ = 68⁰F F₁ = 195°F F(t) = 120⁰F, k = 0.05
120 = 68 + (195 - 68) [tex]e^{-0.05t}[/tex]
[tex]e^{-0.05t}[/tex] = 52/127
[tex]e^{-0.05t}[/tex] = 0.4094
-0.05t = ln (0.4094)
-0.05 t = -0.839
t ≈ 18
Thus, It will take 18 minutes until the coffee is safe to drink.
Learn more about Exponential function from:
https://brainly.com/question/11487261
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