Which of the following is a rational number? A pi B sqrt [3](25) c sqrt (20) D D 3(1)/(2)

The correct answer is D. $3\frac{1}{2}$ is a rational number.<br /><br />A rational number is a number that can be expressed as the quotient or fraction of two integers, where the denominator is not zero. In this case, $3\frac{1}{2}$ can be expressed as the fraction $\frac{7}{2}$, which is the quotient of two integers. Therefore, $3\frac{1}{2}$ is a rational number.<br /><br />Option A, $\pi$, is not a rational number because it cannot be expressed as the quotient of two integers. It is an irrational number, which means it cannot be expressed as a simple fraction.<br /><br />Option B, $\sqrt[3]{25}$, is also not a rational number. The cube root of 25 is an irrational number because it cannot be expressed as the quotient of two integers.<br /><br />Option C, $\sqrt{20}$, is not a rational number either. The square root of 20 is an irrational number because it cannot be expressed as the quotient of two integers.<br /><br />Therefore, the correct answer is D. $3\frac{1}{2}$ is a rational number.