This is an article from May 2014 by CJ Werleman, which appeared on Salon.com, which I think is quite interesting, and some of the observations therein probably apply to African countries more than it applies to the US Education system:-

…There is a defined correlation between literacy, numeracy and technology skills with jobs, rising wages and productivity, good health, and even civic participation and political engagement. Inequality of skills is closely correlated to inequality of income. In short, our education system is not meeting the demands of the new global environment, and the outlook is grim,

…

But the correlation between a strong public education system and social mobility is demonstrated clearly in the OECD report. A 2006 report by Michael A. McDaniel of Virginia Commonwealth University showed that states with higher estimated collective IQ have greater gross state product, citizens with better health, more effective state governments, and less violent crime. In other words, were we to invest more in public education, we’d be instantly more intelligent, healthy, safe, and financially sound….

But the conclusion sums it up best:

…The principal force for convergence [of wealth] — the diffusion of knowledge — is only partly natural and spontaneous. It also depends in large part on educational policies,” writes Thomas Piketty in his 700-page bestseller Capital in the Twenty-First Century. In other words, if we really want to reduce inequality, and if we really want to be a global leader in the 21st century, we need to invest more into our education system, which requires the federal government to ensure the rich and the mega-corporations pay their share…