According to Fidelity Investment Vision Magazine, the average weekly allowance of children varies directly as their grade level. In a recent year, the average allowance of a 9th-grade student was 9.66 dollars per week. What was the average weekly allowance of a 5 th-grade student?​

The average weekly allowance of a 5th grade student as calculated using direct variation with the information provided by Fidelity Investment Vision Magazine is 5.367 dollars per week.

The question given is a direct variation problem:

Let:

• Average weekly allowance =

• Grade level =

If Average weekly allowance varies directly as grade level , then , then the direct variation between the variables can be expressed as :

Where ,   = constant of proportionality

We can obtain the value of k from the given values of a and g

Our equation becomes:

Hence, the average weekly allowance for a 5th grade student is :

(rounded to 3 decimal places)

Hence, using proportional relationship, the average weekly allowance for a 5th grade student is

Learn more about direct variation here: