The price of oil justifies the price of gas?

In my research paper, i want it to be aware to the people of the public that the price of gas hasn't actually been very fair. The fact that the price of oil has dropped 50% since the middle of July and gas prices are just now starting to go down. There is something strange here. Why has the price of oil dropping so dramatically not cause the price of oil to be so cheap. I would think that this would lead to cheaper prices to the public to be fair. But, oil companies aren't being honest, or there are some facts that aren't too accurate. The price of gas should be going down as the price per barrel of oil keeps going down.