Math

Question Exponential drug decay: A patient has 400mg400 \mathrm{mg} of a drug decreasing by 7%7 \% per hour. Identify the correct equation: f(x)=4000.93xf(x)=400 \cdot 0.93^{x}

Studdy Solution

STEP 1

Assumptions
1. The initial amount of the drug in the patient's system is 400mg400 \mathrm{mg}.
2. The drug decreases by 7%7\% each hour.
3. The function f(x)f(x) represents the amount of drug in the patient's system after xx hours.

STEP 2

Understand the nature of exponential decay. When a quantity decreases by a certain percentage each time period, it can be modeled by an exponential decay function.
f(x)=P(1r)xf(x) = P \cdot (1 - r)^x
where: - PP is the initial amount, - rr is the decay rate (as a decimal), - xx is the number of time periods.

STEP 3

Convert the percentage decrease to a decimal to find the decay rate.
7%=7100=0.077\% = \frac{7}{100} = 0.07

STEP 4

Subtract the decay rate from 1 to find the base of the exponential function.
1r=10.07=0.931 - r = 1 - 0.07 = 0.93

STEP 5

Write the exponential decay function using the initial amount and the base found in the previous steps.
f(x)=4000.93xf(x) = 400 \cdot 0.93^x

STEP 6

Identify the correct equation from the given options that matches the exponential decay function derived in the previous step.
The correct equation is:
f(x)=4000.93xf(x) = 400 \cdot 0.93^x

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