$\Delta T = 2.12\sqrt{\left( \frac{\Delta m}{m}\right) ^{2} + \left( \frac{\Delta g}{g}\right) ^{2}}$<br>
$\Delta T = 2.12\sqrt{\left( \frac{\Delta 0.01}{.25}\right) ^{2} + \left( \frac{\Delta 0.01}{9.80}\right) ^{2}}$<br>
$\Delta T = 2.12\sqrt{\left( 0.04\right) ^{2} + \left( 0.001\right) ^{2}}$<br>
$\Delta T = 2.12\sqrt{\left( 0.0016 \right) + \left( 1.041x10^{-6} \right)}$<br>
$\Delta T = 2.12\sqrt{0.0016}$<br>
$\Delta T = 2.12 * 0.04$<br>
$\Delta T = 0.084$<br>