If pMPl > wl, then should the firm increase or decrease the amount of

factor 1 in order to increase profits?

The firm should increase the amount of factor 1 in order to increase profits. This is because when pMPl is greater than wl, the marginal product of factor 1 is greater than the wage rate of factor 1. This means that the firm can increase its profits by increasing the amount of factor 1 used in production.