Some rate-type proposed estimators of population variance, which use known skewness co- efficients for auxiliary information in simple random sampling, are introduced. Ratio-type estimators combined by taking a weighted average of these proposed estimators are also presented. The mean square error (MSE) expressions of the proposed estimators are expressed up to the first order of approximation. After comparing MSEs of some competing estimators, it is shown theoretically that the proposed combining ratio estimators perform better than the unbiased estimator, and the estimators which were introduced in [3] and [4], and the proposed estimators for simple random sampling. In addition, the results are verified with the aid of Covid-19 datasets.