In a class of 40 students, everyone has either a pierced nose or a pierced ear. the professor asks everyone with a pierced nose to raise his or her hand. seven hands go up. then the professor asked everyone with a pierced ear to do likewise. this time there are 36 hands raised. how many students have piercings both on their ears and their noses?
If we were to display the information given as a Venn diagram, it will make it easy to understand. Look at the attached picture: From it, we can formulate an equation: (7 - x) + x + (36 - x) = 40 Now, just simplify and solve: 43 - x = 40 x = 43 - 40 = 3
