Diagram below
ok so what you do is find area of total-areapond=areaaround
then times that by the height
areatotal=pir^2
r=7.5+2=9.5
aeratotal=pi9.5^2=90.25pi
areapond=pi7.5^2=56.25pi
areaaround=90.25pi-56.25pi=34pi
volume=area times height
34pi m^2
15 cm thick
convert 15cm to m
0.15m
34pi times 0.15=5.1pim^3=16.02m^3
volume=16.0 m^3
if converted to cm
v=16022122.5 cm^3
ok so what you do is find area of total-areapond=areaaround
then times that by the height
areatotal=pir^2
r=7.5+2=9.5
aeratotal=pi9.5^2=90.25pi
areapond=pi7.5^2=56.25pi
areaaround=90.25pi-56.25pi=34pi
volume=area times height
34pi m^2
15 cm thick
convert 15cm to m
0.15m
34pi times 0.15=5.1pim^3=16.02m^3
volume=16.0 m^3
if converted to cm
v=16022122.5 cm^3