A body of density d1 is counterpoised by Mg of weights of density d2 in air of density d. Then the true mass of the body is

Let M0 = mass of body in vacuum.Apparent weight of the body in air = Apparent weight of standard weights in air⇒ Actual weight – upthrust due to displaced air      = Actual weight  – upthrust due to displaced air⇒M0g−M0d1 dg=Mg−Md2 dg⇒​M0=M1−dd21−dd1