Chapter 2 - Set Theory - 2.3 Venn Diagrams and Set Operations - Exercise Set 2.3 - Page 83: 135

$A\cup B=\{1980, 1990, 2000\}$

$A=\{x|x$ was a year in which more than $34\%$ were very happy$\}$ $B=\{x|x$ was a year in which fewer than $14\%$ were not too happy$\}$ $A\cup B=?$ From the graph we can see that: $A=\{1980, 1990\}$ $B=\{1980, 1990, 2000\}$ $A\cup B=\{1980, 1990, 2000\}$