Respuesta :
Answer:
**(a) Differential Equation:**
The differential equation describing the change in excess concentration (y) with respect to time (t) is given by:
\[ \frac{dy}{dt} = -k \cdot y \]
The negative sign indicates a decrease in excess concentration over time, representing the elimination or metabolism of the hormone.
**(b) Time for Next Shot:**
Given \( k = 0.6 \) hour⁻¹, and the excess concentration immediately jumps to 4.2 mg/L, we can use the formula:
\[ y(t) = y_0 \cdot e^{-kt} \]
Where \( y_0 \) is the initial excess concentration. We set \( y(t) = 1.15 \) mg/L to find the time for the next shot.
Solving for t:
\[ 1.15 = 4.2 \cdot e^{-0.6t} \]
\[ t = \frac{\ln\left(\frac{4.2}{1.15}\right)}{-0.6} \approx 2.15887 \] hours
So, after approximately 2.15887 hours, the doctor will have to give the next shot.
**(c) Velocity Constant and Time to Fall:**
Given the initial rate of fall (\( \frac{dy}{dt} \)) is 0.6 mg/L/hour and the initial excess