In 1971 , Y.Nagendra and G. Rai concerned with the economic design for con trolling the mean of non-normal variables. Their procedure consists of two equations to get the economic design. In this article, our procedure only consists of solving an explicit equation for h (sampling interval) in terms of n (sample size) and k (control limit factor). We conclude that our model is not only more accurate, more applicable, and more flexible, but also simpler to solve than Y.Nagendra and G.Rai's model.