If a tuning fork of frequency ( f _ 0 )340Hz and tolerance ± 1 % is...

$\text{V} = {2 f}_{0} \left({l}_{2} - {l}_{1}\right)<br/><br/>\text{let} {l}_{2} - {l}_{1} =$x$<br/><br/>${l}_{1} = \left(\text{24.0} \mathop{+}_{¯} \text{0.1}\right) \text{cm}

${l}_{2} = \left(\text{74.70} \mathop{+}_{¯} \text{0.01}\right) \text{cm}<br/><br/>${l}_{2} - {l}_{1} = \left(\text{50.70} \mathop{+}_{¯} \text{0.11}\right) \text{cm}

\dfrac{\Delta x}{x} = \left(\dfrac{\text{0.11}}{\text{50.70}}\right)

\Delta$x$\text{%} = \dfrac{\text{0.11}}{\text{50.70}} \times \text{100}

=\text{0.22%}

\Delta \text{V} \text{%} = \Delta {f}_{0} \text{%} + \Delta$x$\text{%}

=\text{1.22} \text{%}

=\text{1.2} \text{%}