Consider a sample of beams with circular cross section. The diameters have mean $/bar(d)$

and standard deviation $s_d=\frac{0\mathrm{.}03}{b}ar(d).$ Taking the uncertainty of the diameter as

$u_d=s_d,$ the relative uncertainty of the diameter is $\frac{u_d}{/}$bar $(d)=0\mathrm{.}03,$ or $3\%.$ What is

the relative uncertainty of the cross$-$sectional area, expressed as a percentage?

Question $11$

Consider a sample of beams with circular cross section. The diameters have mean

$10\mathrm{.}7mm$ and standard deviation $0\mathrm{.}27mm.$ What is the bending moment of inertia for

this sample of beams, expressed in $mm4?$