Answer
$$\approx 1.625 \% $$
Work Step by Step
We can write as: $dA=\pi b \ da+\pi a db $
and at $(10,16)$, we have: $dA=16\pi \ da+10\pi db $
When $da=\pm 0.1,$ and $ db=\pm 0.1$
So, $dA=\pm 26(\pi) (0.1)=\pm 2.6 \pi$
The estimated change in $A$ is:
$dA=\dfrac{dA}{A} \times 100=|\dfrac{2.6 \pi}{160 \ \pi} \times 100 | \approx 1.625 \% $
