Question

write the following solution in interval notation: z < 20

Explanation:

Step1: Recall interval notation rules

For \( z < 20 \), the solution includes all real numbers less than 20. In interval notation, we use \((-\infty, a)\) when \( x < a \) (open interval at \( a \) since \( a \) is not included), and \( -\infty \) is always in an open interval.

Step2: Match with options

The inequality \( z < 20 \) translates to the interval \((-\infty, 20)\). The first option (and the second, as they are the same) is \((-\infty, 20)\), the third has a closed bracket (including 20, which is wrong as \( z < 20 \) not \( z \leq 20 \)), and the fourth is for \( z > 20 \).

Answer:

A. \((-\infty, 20)\) (and the second option is the same, so either the first or second option with this interval)