10 questions (and answers) to test your knowledge of aging

Aging is here to stay as more of us get older and live longer.  
To test some of your knowledge (without exams or grades) about aging, take the following quiz. It is based on the “Facts on Aging Quiz” developed by emeritus professor of gerontology and sociology Linda Breytspraak and Lynn Badura, both from the University of Missouri, Kansas City. I have reworded some of the questions and updated the answers. 
1. People age 65 and older currently make up about 10 pe