Questions: Survey of Calculus (7)
Section 2.5 Activity
Question 1, 2.5.1-P8
HW Score: 0%, 0 of 8 points
Part 1 of 4
Points 0 of 1
1 ← A chemical substance has a decay rate of 7.6% per day. The rate of change of an amount N of the chemical after t days is given by dN/dt=-0.075 N.
a) Let N0 represent the amount of the substance present at t=0. Find the exponential function that models the decay
b) Suppose that 600 g of the substance is present at t=0. How much will remain after 6 days?
c) What is the rate of change of the amount of the substance after 6 days?
d) After how many days will half of the original 600 g of the substance remain?
a) N(t)=
Transcript text: Survey of Calculus (7)
Section 2.5 Activity
Question 1, 2.5.1-P8
HW Score: $0 \%, 0$ of 8 points
Part 1 of 4
Points 0 of 1
$1 \leftarrow$ A chemical substance has a decay rate of $7.6 \%$ per day. The rate of change of an amount N of the chemical after t days is given by $\frac{\mathrm{dN}}{\mathrm{dt}}=-0.075 \mathrm{~N}$.
a) Let $\mathrm{N}_{0}$ represent the amount of the substance present at $t=0$. Find the exponential function that models the decay
b) Suppose that 600 g of the substance is present at $t=0$. How much will remain after 6 days?
c) What is the rate of change of the amount of the substance after 6 days?
d) After how many days will half of the original 600 g of the substance remain?
a) $N(t)=\square$
Solution
Solution Steps
Step 1: Modeling the Decay
The exponential decay function is modeled as $N(t) = N_0 e^{-kt}$, where $N(t)$ is the amount of substance remaining after $t$ days.
Given: $k = 0.076$, $N_0 = 600$. The decay function becomes $N(t) = 600 e^{-0.076t}$.
Step 2: Remaining Amount After t Days
Using the decay function, the remaining amount after $t = 6$ days is $N(t) = 600 e^{-0.076*6} = 380.29$.
Step 3: Rate of Change After t Days
The rate of change at $t = 6$ days is given by $\frac{dN}{dt} = -kN_0 e^{-kt} = -28.9$.
Step 4: Time for Half of the Substance to Remain
To find when half of the substance remains, we solve $N(t) = \frac{N_0}{2}$ for $t$, which gives $t = \frac{\ln(2)}{k} = 9.12$ days.
Final Answer:
The remaining amount after 6 days is 380.29.
The rate of change after 6 days is -28.9.
The time for half of the substance to remain is approximately 9.12 days.