Final answer:
The plus-minus sign after a number frequently indicates the positive or negative deviation from a reference value, such as in z-scores where positive means above the mean and negative indicates below it. These signs also follow arithmetic rules in adding and multiplying numbers.
Step-by-step explanation:
In mathematics and statistics, the plus-minus sign (+ and -) after a number score typically indicates a positive or negative deviation from a reference value.
For example, in the context of z-scores, a positive z-score means the data point is above the mean, while a negative z-score indicates it is below the mean. Similarly, in grading or scoring systems, a '+' might signify a score above a certain threshold, while a '-' could indicate a score below it.
When performing basic arithmetic operations, the rules for combining numbers with different signs are important. Adding two positive numbers results in a positive answer, while the product of two negative numbers is also positive. If numbers with opposite signs are multiplied, the result is negative.
In the context of an ART scale, the '+' and '-' after numbers would follow similar mathematical rules in terms of denoting a positive or negative value in relation to a reference point or scale.