Chem help!?

Question

A gas of unknown molecular mass was allowed to effuse through a small opening under constant pressure conditions. It required 52 s for 1.0 L of the gas to effuse. Under identical experimental conditions it required 24 s for 1.0 L of O2 gas to effuse. Calculate the molar mass of the unknown gas. (Remember that the faster the rate of effusion, the shorter the time required for effusion of 1.0 L; that is, rate and time are inversely proportional.)
g/mol

Answer 1

24/52 = sqrt(32/x)

or 6/13 = sqrt(32/x)

or x = 32*169/36 = 155.22