Answer
$0.011Kg.m^2$
Work Step by Step
We know that
$T=2\pi \sqrt{\frac{l}{g}}\sqrt{\frac{I}{ml^2}}$
This can be rearranged as
$I=\frac{mglT^2}{4\pi^2}$
We plug in the known values to obtain:
$I=\frac{0.98(9.81)(0.084)(0.73)}{4\pi^2}$
$I=0.011Kg.m^2$
