## Basic College Mathematics (9th Edition)

2 or greater: $\frac{5}{6}$ 4 or less: $\frac{4}{6}$, or $\frac{2}{3}$ 9 years: $\frac{2}{6}$, or $\frac{1}{3}$
There are 6 bills total. 5 out of the 6 have a lifespan of 2 years or greater (5, 10, 20, 50, and 100). This is represented by the fraction $\frac{5}{6}$. 4 of the 6 have a lifespan of 4 years or less (1, 5, 10, and 20). This is represented by the fraction $\frac{4}{6}$, which can be simplified to $\frac{2}{3}$. 2 of the 6 have a lifespan of 9 years (50 and 100). This is represented by the fraction $\frac{2}{6}$, which simplifies to $\frac{1}{3}$.