Ralph opened a savings account with a deposit of $100. every month after that, he deposited $20 more.
a. why is the relationship described not proportional?
b. how could the situation be changed to make the situation proportional?

Part a) Why is the relationship described not proportional?

we know that

A relationship between two variables, x, and y, represent a direct variation or proportional if it can be expressed in the form

In this problem

Let

x-------> number of months

y-------> amount of money in the saving account

The problem can be modeled by the following equation

So

In the proportional situation for the value of x equal to zero , the value of y is also equal to zero

therefore

the answer Part a) is

The relationship is not proportional because his savings account started with $

Part b) How could the situation be changed to make the situation proportional?

To make it proportional Ralph's savings account needs to start with $

so

we make the initial deposit equal to zero, maintaining the monthly deposits of $, the equation would be

$9.89

step-by-step explanation:

9.90 = p x .06 x .25 (3/12 changed to a decimal)

9.90 = p x 0.015

9.90 - 0.015 = p

9.89 = p