Here are the solutions to the problems: 4. Identify whether each of the following is rational or irrational. a) $\frac{1}{3}$: This is a fraction of two integers, so it is rational*. b) $\sqrt{2}$: The decimal representation of $\sqrt{2}$ is non-terminating and non-repeating, so it is irrational*. c) $0.75$: This can be written as $\frac{3}{4}$, so it is rational*. d) $\pi$: The decimal representation of $\pi$ is non-terminating and non-repeating, so it is irrational*. e) $7$: This can be written as $\