b. McKinsey's report argues that Mexico is a "two-speed" economy, where the productivity of formal firms grow and productivity of the informal firms do not, and the productivity of formal firms is higher than that of the informal firms. Furthermore McKinsey argues that that is because informal firms do not have access to resources (such as access to the banking system) that formal firms do. If this argument is correct, what would you see in terms of the differences in productivity of formal vs. informal firms in Mexico, and why