Which statement is a good definition?
You are a teenager if and only if you are 15 years old.
You are not a teenager if and only if you are less than 13 years old.
You are 13 to 19 years old if and only if you are a teenager.
You are 15 years old if and only if you you are not an adult.
My answer: C
Your answer, C, is correct. "You are 13 to 19 years old if and only if you are a teenager" is a good definition because it accurately defines the age range of teenagers.
To determine which statement is a good definition, let's break down each statement and analyze them:
Statement A: "You are a teenager if and only if you are 15 years old."
This definition is not accurate because it implies that only 15-year-olds can be teenagers, which is not true. There are individuals between the ages of 13 and 19 who can also be considered teenagers.
Statement B: "You are not a teenager if and only if you are less than 13 years old."
This is also an inaccurate definition. It suggests that anyone younger than 13 cannot be a teenager, which is incorrect. Teenagers are typically between the ages of 13 and 19.
Statement C: "You are 13 to 19 years old if and only if you are a teenager."
This definition is accurate and aligns with the generally accepted age range of teenagers. Teenagers are commonly defined as individuals who are between the ages of 13 and 19.
Statement D: "You are 15 years old if and only if you are not an adult."
While this statement is true, it does not provide a comprehensive definition of a teenager. It only specifies that at 15 years old, a person is not yet an adult.
Therefore, the correct answer is statement C: "You are 13 to 19 years old if and only if you are a teenager."