Answer
$
351.3 $ $Hz$;
the musical note $F.$
Work Step by Step
Based on the given table, with a musical note of G, the pitch is $392.00$ $Hz.$
Using the given formula, $
h=\dfrac{a}{1-\dfrac{s}{770}}
,$ then
\begin{array}{l}\require{cancel}
392=\dfrac{a}{1-\dfrac{80}{770}}
\\\\
392=\dfrac{a}{\dfrac{770}{770}-\dfrac{80}{770}}
\\\\
392=\dfrac{a}{\dfrac{690}{770}}
\\\\
392=a\div\dfrac{690}{770}
\\\\
392=a\cdot\dfrac{770}{690}
\\\\
392=\dfrac{770}{690}a
\\\\
\dfrac{690}{770}(392)=\left(\dfrac{770}{690}a\right)\left(\dfrac{690}{770}\right)
\\\\
\dfrac{690(392)}{770}=a
\\\\
a=351.27272727272727272727272727273
.\end{array}
Rounded to the nearest tenth, the pitch the observer hears is $
351.3 $ $Hz.$ This pitch is closest to the musical note $F.$
