A 20mg sample of a compound is dissolved in 5.0 mL of water and extracted with 2.5 mL of heptane. After seperation of the layers, the heptane layer is found to contain 15 mg of the compound. What is the partition cofficient of the compound,

K(hept/water)

Ko/a = [(organic phase)/(aq phase))

Plug in 15/2.5 for organic phase
Plug in 5/5 for aq phase.

Solve for Ko/a = ??