Speculative investing weakened the stability of the stock market because people were "over-investing" in companies--meaning that that companies were becoming highly over-valued, which led to an economic "bubble" that eventually popped in the Crash of 1929.
A rate allows us to compare two numbers or measurements and give them a value. This helps us in real life to make everyday activities simpler. For example: you have to take a photocopy as quickly as possible and you have two photocopiers. The first draws 10 copies per minute and the second only 5 copies per minute. Using the rates you can know that the first option in better because you will have the double of copies in the same time. Another example is a place where you get 2 pizzas for $10 and another where you get 1 for $8. The rates help you to know that in the first place they give you 1 pizza for $5 (10÷2=5) so it is a cheaper option.
The Roman Empire fell because it messed with Germanic tribe for years. The Germanics were tired of this and a group a barbarians(Goths) approached the Roman Empire and took over. The romand were also suffering from financial crisis from constant wars.
He proved that baseball wasn't just a white sport, that not just African Americans, but all "colored" races could play/do what they wanted as long as they put heart into it.
