Given –

$V=20\times 15 \times 10m^{3}$

$T=3 sec$

Solution –

We know that

1) $T=0.161\times \dfrac {V}{\sum aS}$

$\sum aS=0.161 \times \dfrac {(20\times 15 \times 10 )}{3}$

$\sum aS =80.5$ Sabines

2)  $a=\dfrac {\sum aS}{\sum S}= \dfrac {80.5}{2(20\times 15 +15 \times 10 + 10 \times 20)} =0.062$

∴ Total …