The answer is:  "1,200,000,000 people" ;  or , write as:  "1.2 billion people"
              (in the world) lived on less than $1 per day in the year 2002. "
_____________________________________________________________
 20% of 6 billion =  ? ;
20% = 20/100 = 2/10 = 0.2 .
6,000,000,000 * 0.2 =
1,200,000,000 people .
______________________________________________________