This nal project is a review of Kadilar and Chingi [Journal of Modern Applied Statistical Method, 35 (2006), 111{115] which discusses three estimators of ratio population variances ^ S2 KC1, ^ S2 K C2 and ^ S2 KC3 of the population of variables Y using known auxiliary variables X on simple random sampling. The three estimators ^ S2 K C1, ^ S2 KC2 and ^ S2 KC3 are the modied of ratio…