A chemical plant produces 5000 kg/hr of a certain chemical. The raw material used in the production process contains impurities that must be removed before the reaction. The purity of the raw material is 80% and the impurities must be reduced to less than 1% in the final product. A purification process is available that can remove 95% of the impurities. What is the minimum amount of raw material required to produce the required amount of product per hour?