I'm working on two problems that I need help on.

(1) The radius of a circle is to be measured and its area computed. If the radius can be measured to an accuracy of 0.001 in and the area must be accurate to 0.1in^2, estimate the maximum radius for which this process can be used.

(2) If pV=20 and p is measured as $\displaystyle 5\pm0.02$, estimate V.

Here are the formulas I have been using for these problems (out of Schaum's Calculus, 4th ed.):

$\displaystyle f(x+\Delta x) \sim f(x)+\dot f(x)*\Delta x)$

$\displaystyle \displaystyle x_{n+1}=x_n+\frac{f(x_n)}{f\prime(x_n)}$

I'm not requesting that someone work out the problems for me, just help me with where to start. Thanks