Pharmacy exam 2017-11-06

Degrees: Pharmacy and Biotechnology
Date: Nov 6, 2017

Question 1

Adenoma is a benign tumor, which grows usually in spherical shape. Suppose the rate of growth of the radius of a certain adenoma is equal to half the size of the radius per second; compute the rate of growth of the volume of the tumor when the radius is 5mm.

If the measurement of the radius has a possible error of $\pm 0.01$mm, what will be the error in the measurement of the volume?

Note: The volume of a sphere of radius $r$ is equal to $\frac{4}{3}\pi r^3$.

Rate of growth of the volume: $250\pi$ mm³/s.
Error in the volume: $\pi$ mm³.

Question 2

The weight of a baby during the first few months of life grows at a rate proportional to the reciprocal of the weight. Suppose a baby’s weight was 3.3 kg at birth, and 4.3 kg a month later.

  1. What will be the weight of the baby one year after birth?
  2. When will the weight be equal to 8 kg?
  3. Is this model of the weight good to determine the weight of a person during his whole life?

Let $t$ the time and $w(t)$ the weight of the baby at time $t$.

  1. Differential equation: $w’=\dfrac{k}{w}$
    Particular solution: $w(t)=\sqrt{7.6t+10.89}$.
    $w(12)=10.1$ kg.
  2. At 7 months.
  3. No, because the function is always increasing.

Question 3

The function $f(x,y)=ye^{-x^2-\frac{1}{2}y^2}$ gives the quantity $z=f(x,y)$ of a substance during a chemical process, depending on the quantities $x$ and $y$ of two other substances.

  1. Compute the maximum value of $z$ assuming that $x\geq 0$ and $y\geq 0$.
  2. What will be the variation of $z$ at $x=1$ and $y=0$ when $x$ increases twice as much as $y$?
  3. Compute the second degree Taylor polynomial of $f$ at the point $(1,0)$.

  1. $f$ has a local maximum at $(0,1)$ and the maximum value is $z=f(0,1)=1/\sqrt{e}$.
  2. Directional derivative of $f$ at $(1,0)$ along the direction of $v=(2,1)$: $f’_v(1,0)=\frac{1}{e\sqrt{5}}$.
  3. $P^2_{f,(1,0)}(x,y)=\displaystyle\frac{-2xy+3y}{e}$.

Question 4

Given $h(t)=(t\cos(t), \cos(t), \ln(t^2+1)),$ compute the tangent line and normal plane to the trajectory determined by $h$ at the point $(0,1,0)$.

  1. Tangent line: $(t,1,0)$.
  2. Normal plane: $x=0$.
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