Question 122·Medium·Command of Evidence
Average Daily Water Consumption Before and After a Citywide Conservation Program
| Customer Type | Before Program (Year 1) | After Program (Year 3) |
|---|---|---|
| Residential | 120 million gallons | 90 million gallons |
| Commercial | 65 million gallons | 58 million gallons |
| Industrial | 40 million gallons | 38 million gallons |
City officials stated, “Our voluntary conservation program was effective, particularly among households; it resulted in a significantly larger reduction in residential water use than in industrial water use.” Which statement based on the data in the table best supports the officials’ claim?
For data-support questions, first restate the claim in your own words and note exactly which categories are being compared and what relationship is claimed (greater, smaller, equal, etc.). Then compute any needed differences or percentages directly from the table, and eliminate choices that are (1) numerically incorrect, or (2) about the wrong comparison. Finally, pick the statement that most directly and accurately restates the relationship the claim describes, using the data you just computed.
Hints
Focus on what needs to be compared
The officials are making a claim about residential versus industrial water use. Make sure you focus on those two rows of the table.
Compute the changes, not just look at final numbers
For both residential and industrial customers, subtract the “After Program” value from the “Before Program” value to see how much their usage decreased.
Check which answer really backs up the claim
Eliminate any choices that don’t compare both residential and industrial customers or that are not accurate according to the numbers in the table.
Step-by-step Explanation
Identify what the officials are claiming
The officials say the program was “particularly among households” and that it caused “a significantly larger reduction in residential water use than in industrial water use.”
So you need an answer that:
- Talks about residential (household) water use
- Directly compares it to industrial water use
- Shows that the reduction for residential is much larger than for industrial
Calculate the change for residential and industrial customers
Use the table to find how much water use changed for each type.
- Residential: from 120 to 90 million gallons
- Change: million gallons decrease
- Industrial: from 40 to 38 million gallons
- Change: million gallons decrease
So residential customers reduced their daily use by 30 million gallons, while industrial customers reduced theirs by 2 million gallons.
Connect the numbers to the idea of “significantly larger”
Compare the size of the two decreases:
- Residential decrease: 30 million gallons
- Industrial decrease: 2 million gallons
A decrease of 30 is much larger than a decrease of 2. This is what “significantly larger reduction” is describing.
Now look for the answer choice that accurately restates this idea using the data.
Match the claim to the best supporting statement
You want the choice that says the drop in residential use was much bigger than the drop in industrial use, using the raw differences.
That is exactly what choice D) the absolute decrease in residential water consumption was substantially greater than the absolute decrease in industrial water consumption says, so D is the correct answer.