Question

After replacing her old air conditioner with a new, energy-efficient unit, Paula's electric bills increased.
Each of the following, if true, contributes to an explanation of the increase mentioned above EXCEPT:

• A. Paula's electricity costs increased by 15 cents per kilowatt hour after she replaced her air conditioner.
• B. Soon after the new air conditioner was installed, Paula adopted a child, doubling the size of her household.
• C. Paula installed an electricity-intensive indoor tanning bed after she replaced her air conditioning unit.
• D. The new air conditioner uses a smaller share of the electricity used by Paula's home than did the old unit.
• E. Following the installation of her new air conditioner, Paula's neighborhood experienced a prolonged and severe heat wave, requiring heavy use of the new unit.

Hint:

In "Explain the Paradox, EXCEPT" questions, you are looking for the odd one out. Four of the choices will resolve the apparent contradiction by introducing a new piece of information (e.g., a price increase, an increase in usage, etc.). The correct answer will be the one that is irrelevant, restates part of the premise, or deepens the paradox.

Answer 1

The Correct Option is D

Step 1: Understanding the Concept:
This is a paradox question with a twist. The paradox is that an action expected to cause a decrease (installing an energy-efficient AC) has resulted in an increase (higher electric bills). We are asked to find the option that does NOT help explain this surprising outcome. Therefore, four of the options will provide a possible reason for the increased bill, and one will not.

Step 2: Key Formula or Approach:
The total electric bill is a product of two factors:
\[ \text{Total Bill} = (\text{Total Electricity Consumed in kWh}) \times (\text{Cost per kWh}) \] To explain why the total bill increased despite the new AC being more efficient, one or both of these factors must have increased enough to offset the savings from the new appliance.

Step 3: Detailed Explanation:
Let's analyze each option to see if it provides a plausible explanation for the increased bill:
- (A) Paula's electricity costs increased by 15 cents per kilowatt hour...: This directly addresses the "Cost per kWh" part of the formula. A significant price hike from the utility company could easily lead to a higher bill, even if Paula's total electricity consumption decreased slightly. This explains the paradox.
- (B) ...Paula adopted a child, doubling the size of her household.: A larger household would almost certainly lead to an increase in overall electricity consumption (more lights, laundry, electronics, etc.). This increase in "Total Electricity Consumed" could easily outweigh the savings from the new AC. This explains the paradox.
- (C) Paula installed an electricity-intensive indoor tanning bed...: Similar to option (B), adding a new, high-power appliance would increase the "Total Electricity Consumed," potentially by a large amount. This could easily account for the higher bill. This explains the paradox.
- (D) The new air conditioner uses a smaller share of the electricity used by Paula's home...: This statement is a consequence of the new AC being energy-efficient, not a reason for the total bill increasing. It means that the AC is doing its job as expected (being more efficient relative to other appliances). This statement actually deepens the paradox because it confirms the AC's efficiency but offers no explanation for why the overall bill went up.
- (E) ...Paula's neighborhood experienced a prolonged and severe heat wave...: A heat wave would force Paula to run the new AC for much longer hours than she ran the old one. Even if the new unit uses less power per hour, a drastic increase in the number of hours it runs could lead to higher total consumption from the AC than before. This explains the paradox.

Step 4: Final Answer:
Options (A), (B), (C), and (E) all provide new information that could logically explain why Paula's total electric bill increased. Option (D) does not provide an explanation; it merely confirms that the new appliance is, in fact, energy-efficient, which makes the situation more puzzling, not less. Therefore, it is the correct answer for this EXCEPT question.