Increase in per capita income and developing productivity are the major concerns of the countries. In this project we try to investigate the hypothesis of adding the risk of removing income tax at a specific time with the open economy hypotheses (exchange rate integrity) to Solow growth model which could increase the per capita income significantly. this theoryhas not been taken into account in Solow growth model and through optimizing the convergence rate that leads to stable convergance rate with the the effective parameters of risk that considers the closed economy as well causes increase in constant population (the constant efficient work force) and technological development of the countries. The main aim of the study was to investigate the risk for increasing convergence rate, increase in welfare consumption of the individuals especially the workers and increase in per capita income of the country using static and dynamic models.