Answer
about $1.26$
Work Step by Step
Given$ \displaystyle \quad\frac{I_{2}}{I_{1}}=10^{0.1(D_{2}-D_{1})}$
when $D_{2}=D_{1}+1$
$\displaystyle \frac{I_{2}}{I_{1}}=10^{0.1(D_{1}+1-D_{1})}=10^{0.1}\approx 1.259$
The second sound is about $1.26$ times as intense as the first.
