About how accurately must the interior diameter of a 10-m high cylindrical storage tank be measured to calculate the tank's volume within 1% of its true value?. . About how accurately must the tank's exterior diamter be measured to calculate the amount of paint it will take to paint the side of the tank to within 5% of the true amount?

Verified Answer :

Hagrid

V = (pi) R^2 H 

dV = 2 (pi) R H (dR) 

dV/V = 2 (pi) R H (dR) / (pi) R^2 H = 2 (dR) / R 

2 (dR) / R = dV/V 

dR/R = 1/2 dV/V 

dV/V 100 is the percentage error in volume calculation = 1% 

dV/V = 1/100 = .01 

Therefore, dR/R = 1/2 dV/V = 1/2 .01 = .005 or 0.5% 



The percentage error in measuring the radius (or the diameter) must be within 0.5% of the true radius (or the diameter) in order to calculate the tank's volume within 1% of its true value.

Answer: The correct answers are half percentage and 2.5 percentage.

Explanation:

The volume of the cylinder is as follows;

\(V=\pi r^{2}h\)                                     ....... (1)

Here, r is the radius and h is the height.

On differentiating on the both side.

\(dV=2\pi rhdr\)                                  ........ (2)

Divide (2) by (1).

\(\frac{dV}{V}=\frac{2\pi rhdr}{\pi r^{2}h}\)

\(\frac{dV}{V}=\frac{2dr}{dr}\)

\(\frac{dr}{r}=\frac{1}{2}\frac{dV}{V}\)

Put \(\frac{dV}{V}=1%\)

\(\frac{dr}{r}=\frac{1}{2}1%\)

\(\frac{dr}{r}=.005\)

\(\frac{dr}{r}=0.5%\)

To get the volume within 1% measure the radius (or the diameter) must be within half percentage of the true radius (or the diameter).

\(\frac{dr}{r}=\frac{1}{2}\frac{dV}{V}\)

Put \(\frac{dV}{V}=5%\)

\(\frac{dr}{r}=\frac{1}{2}5%\)

\(\frac{dr}{r}=0.025\)

\(\frac{dr}{r}=2.5%\)

To get the volume within 2.5% measure the radius (or the diameter) must be within half percentage of the true radius (or the diameter).