How can graphs be used in the business world?
In a huge number of situations. See below
Can be used in sales evolution, in stock price evolution, comparing sales in a specific period of time between competitors, Comparing product prices in a company, for calculate market share of your products in a specific market,, etc, etc
To calculate sales variances in price and volume and his evolution, revenue evolution even forecasting for get new investors in your business,..
You can graph using a excel spreadsheet whichever data you want. Even you can explore several examples looking at google