These three charts each plot one value only: respectively, the ask price, average price, or bid price.
If these lines were all plotted on the same graph (as shown in the image below), the ask price would be higher than the other lines, the bid price lower, and the average price midway between the two.

© 1996 - 2008 OANDA Corporation. All rights reserved. All Registered Trade Marks used on this Website, whether marked as Trade Marks or not marked, are declared to belong to their respective owner(s). OANDA Corporation owns Trade Marks of all its "FX" products.