approximately 9 out of 10 smokers began smoking before the age of 21. In a group of 400 smokers, about how many of them started before they reached their 21st birthday?
You can create an equation to solve for x: [tex]9/10=x/400[/tex] Cross Multiply. [tex]9*400=10*x[/tex] [tex]3600=10x[/tex] Divide both sides by 10. [tex](3600)/10=(10x)/10[/tex] The Answer Is: [tex]360=x[/tex]
Out the 400 smokers, approximately 360 of them started smoking before age 21.
