$\quad T_{1}=273+20=293 \mathrm{K}$
$$
T_{2}=273+40=313 \mathrm{K}
$$
The velocity of sound wave in gases or air is given by
$$
v=\sqrt{\frac{\gamma R T_{1}}{M}}
$$
where, $\gamma=$ Ratio of $C_{p} / C_{V}$
$$
\begin{array}{l}R=\text { gas constant } \\ \qquad \begin{array}{l}v_{1}=\sqrt{\frac{\gamma R T_{1}}{M}} \\ v_{2}=\sqrt{\frac{\gamma R T_{2}}{M}}\end{array} \\ \frac{v_{1}}{v_{2}}=\sqrt{\frac{T_{1}}{T_{2}}}=\sqrt{\frac{293}{313}}\end{array}
$$
$\begin{aligned} \text { Given, } v_{1}=344.2 \mathrm{m} / \mathrm{s} & \\ \begin{aligned} \therefore \quad v_{2} &=v_{1} \sqrt{\frac{313}{293}} \\ &=344.2 \times \sqrt{1068} \\ &=344.2 \times 103 \mathrm{m} / \mathrm{s} \\ &=35575 \mathrm{m} / \mathrm{s} \\ &=356 \mathrm{m} / \mathrm{s} \end{aligned} \end{aligned}$