Proportionality indicates how quantity vary in relation with other quantities. There are two types of proportionality, that is direct proportionality where an increase or a decrease in a quantity causes a corresponding increase or decrease in the other variable and inverse proportionality where decrease in a variable causes an increase in the other variable and vicevarsa. In this case the 15 paperclips have a total weight of 2 grams therefore each clip contributes a weight of 0.0133 grams, thus increasing the paperclips also increases the total weight. Thus, the number of paper clips is direct proportional to the total weight