Hi there hopes this helps
Total volume of the tank is 5000 cubic units
Volume of liquid=60%*5000=3000 cubic units
the height of the fluid will be found as follows
V=πr²h
where:
r=20/2=10 units
hence:plugging in the values and solving for h we get:
3000=π×(10²)×h
thus
h=3000/(100π)
h=9.5292966
h=9.5293 unit