simple maths quesion. thankyou?

Question

a drop of oil, whose volume is 0.9mm^3 (9x10^-10 m^3) spreads out on the surface of water to form a circular disc of a diameter 84cm.

Q. what is the thickness of this disc. need work out pls

Answer 1

volume of the disc = piX(radius)^2Xthickness
volume of the drop is given

just equate these two and calculate thickness.

Answer 2

Just divide the volume of the drop by the circular area.
A = pi r^2
A = pi (42)^2
A = 5542 cm^2
A = 554200 X mm^2
thickness = volume/area
thickness = 0.9/554200
thickness = 1.624 X 10^(-6) mm

Answer 3

uhh simple..