c
\(d = density\,of\,cylinder\)

\(A = area\,of\,cross - section\,of\,cylinder\)

Using law of floatation,

\(Weight\,of\,cylinder = Upthrust\,by\,two\,liquids\)

\(L \times A \times d \times g = n\rho  \times \left( {pL \times A} \right)g + \rho \left( {L - pL} \right)Ag\)

\(d = np\rho  + \rho \left( {1 - p} \right) = \left( {np + 1 - p} \right)\rho \)

\(d = \left\{ {1 + \left( {n - 1} \right)p} \right\}\rho \)