Only 53% of adults know how long it takes for the Earth to revolve around the Sun.
Only 59% of adults know that the earliest humans and dinosaurs did not live at the same time.
Only 47% of adults can roughly approximate the percent of the Earth's surface that is covered with water.*
Only 21% of adults answered all three questions correctly.
http://www.sciencedaily.com/releases/2009/03/090312115133.htm