For the purpose of this discussion assume that you are billed monthly based on the actual amount of water used the prior month, not on a levelled "same amount per month" payment plan.
1. Consider your monthly water bill - define the dependent and independent variables used. Remember the dependent will change because of the independent not the other way around. For example crops will grow more (dependent) on the amount of rain (independent) but rain is not impacted by crops. Define at six pairs of dependent and independent variables which will cause the water bill to change.
2. Think about your actual house/apartment and consider three events/relationships (which you have not already identified above) which exist and are predictable indicators of changes in your water bill.
3. Aside from utilities, what other costs in your household budget vary on a predictable basis during the year? Identify 4 cost categories and the events/relationships which would generate a change in cost.
While I do not have access to the book that this question is referring to I should be able to provide the structure of the information the question is asking for.
The question is asking us to look at a monthly water bill and define the dependent and independent variables.
The independent variables are the ones that stand alone and it is not changed by the other variables we are trying to measure (What are independent and dependent variables, n.d.).
- Gallons of water into the house
- Gallons of water for irrigation
- Gallons of water out of the house
The dependent variables are the ones that change depending on several factors, such as how much water you use during the month (What are independent and dependent variables, n.d.).
- Total cost of water into house
- Total cost of water outside
- Sewer ...
This write-up covers dependent and independent variables through the example of a water bill. Numerous examples are included. One source is provided.