(a) The volume V of a growing spherical cell is
V = 4/3pr3,
where the radius is measured in micrometers (1 µm = 10-6m). Find the average rate of change of V with respect to r when r changes from 3 to each of the following. (Round your answers to one decimal place.)
(i) 3 to 6 µm
.......µm3/µm

(ii) 3 to 4 µm
......µm3/µm

(iii) 3 to 3.1 µm
.....µm3/µm

(b) Find the instantaneous rate of change of V with respect to r when r = 3 µm. (Round your answer to one decimal place.)
V'(3) = ......µm3 / µm

Respuesta :

Answer:

(i)=263.9 micrometer square

(ii)=155 micrometer square

(ii)=116.9 micrometer square

(b).37.7 micrometer square

Step-by-step explanation:

Given,

[tex]f\left ( x \right )=V=4/3\Pi r^{3}[/tex]

Average rate of change  V  with respect to  a to b  where a and b are radius

[tex]\frac{\mathrm{d} V}{\mathrm{d} r} =(f\left ( b \right )-f\left ( a \right ))/\left ( b-a \right )[/tex]

(i)  3 to 6 micrometer

[tex]f\left ( 3 \right )=4/3\Pi \times 3^{3}=36\Pi[/tex]                   [tex]f\left ( 6 \right )=4/3\Pi \times 6^{3}=288\Pi[/tex]

[tex]\frac{\mathrm{d} V}{\mathrm{d} r}=\left ( f\left ( 6 \right )-f\left ( 3 \right ) \right )/\left ( 6-3 \right )[/tex]    [tex]=(288\Pi -36\Pi)/3[/tex]

[tex]\frac{\mathrm{d} V}{\mathrm{d} r}=84\Pi =263.893[/tex]       [tex]=263.9[/tex] micrometer square

(ii)  3 to 4

[tex]f\left ( 4 \right )=4/3\Pi 4^{3}=256\Pi /3[/tex]

[tex]\frac{\mathrm{d}V }{\mathrm{d} r}=\left ( f\left ( 4 \right )-f\left ( 3 \right ) \right )/\left ( 4-3 \right )[/tex]

[tex]\frac{\mathrm{d} V}{\mathrm{d} r}=(256\Pi /3-36\Pi)/1=154.985[/tex]

[tex]\frac{\mathrm{d} V}{\mathrm{d} r} =155[/tex]  micrometer square

(iii) 3 to 3.1

[tex]f\left ( 3.1 \right )=4/3\Pi 3.1^{3}=124.788[/tex]

[tex]\frac{\mathrm{d} V}{\mathrm{d} r}=\left ( f\left ( 3.1 \right )-f\left ( 3 \right ) \right )/\left ( 3.1-3 \right )[/tex]

[tex]=\left ( 124.7882-36\Pi \right )/\left ( 3.1-3 \right )[/tex]

[tex]\frac{\mathrm{d} V}{\mathrm{d} r}=116.9091[/tex]

[tex]\frac{\mathrm{d} V}{\mathrm{d} r}=116.9[/tex] micrometer square

(b) At r=3 micrometer

Instantaneous rate

[tex]\frac{\mathrm{d} V}{\mathrm{d} r}=\frac{\mathrm{d} (4/3\Pi \times r^{3})}{\mathrm{d} r}[/tex]

[tex]\frac{\mathrm{d} V}{\mathrm{d} r}=4/3\Pi \times 3r^{3-1}[/tex]

[tex]\frac{\mathrm{d} V}{\mathrm{d} r} =4/3\Pi r^{2}[/tex]

[tex]=4/3\Pi \times 3^{2}=37.699[/tex] micrometer square

[tex]=37.7[/tex] micrometer square