A pharmacist is studying the elimination of a medication from the bloodstream. The mass of the medication in the body is modeled by the equation
m=m0e−kt m = m_0 e^{-kt} m=m0e−ktwhere m0m_0m0 mg is the initial mass administered and mmm mg is the mass in the body after ttt hours.
On average, the biological half-life of this medication is 4.5 hours.
A patient is given a single dose of 300 mg of the medication.
The patient takes the 300 mg dose at 9 am. Use the model to estimate the mass of the medication remaining in the body at 3 pm.
The patient is instructed to ensure that the total mass of the medication in their body does not exceed 350 mg. The patient intends to take a second 300 mg dose. Using the model, find the earliest time they can take this second dose. Give your answer to the nearest minute.
State one reason why the mass of medication predicted by this model might not be accurate for an individual patient.
425 exam-style questions on OCR A Level Maths 1.7 Differentiation, covering 1.7.1 Derivative as gradient of the tangent, 1.7.2 Gradient of the tangent at a point, 1.7.3 Sketching the gradient function, 1.7.4 Second derivatives, 1.7.5 Second derivative as rate of change of gradient, 1.7.6 Convex, concave and points of inflection (A-level only), 1.7.7 Differentiation from first principles for powers of x, 1.7.8 Differentiation from first principles for sin x and cos x (A-level only), 1.7.9 Differentiating x^n, 1.7.10 Differentiating e^(kx) and a^(kx) (A-level only), 1.7.11 Differentiating trigonometric functions (A-level only), 1.7.12 Derivative of ln x (A-level only), 1.7.13 Tangents and normals, 1.7.14 Stationary points, 1.7.15 Increasing and decreasing functions, 1.7.16 Points of inflection (A-level only), 1.7.17 Product and quotient rules (A-level only), 1.7.18 Chain rule (A-level only), 1.7.19 Parametric and implicit differentiation (A-level only), 1.7.20 Constructing differential equations (A-level only), and 1.7 Differentiation. Each one has a worked solution and a mark scheme showing where the marks go.