This study demonstrated the efficiency of an exponential-type estimator under Ranked Set Sampling (RSS) design. For the mathematical expressions, the MSE and Bias had been derived up to 1st and 2nd degree approximation respectively. Family of this proposed estimator has derived also and for efficiency comparison, mathematical conditions have been derived by comparing various existing estimators under RSS design. For the efficiency, a numerical comparison was also done by taking 3 real life population data for high negative correlation, moderate and high positive correlation. On the basis of this proof, it is revealed that exponentially ratio type estimator is most efficient than all other existing estimators.