To determine which house had the lowest cost per day, we can analyze the costs from the data provided for House 1 and the graph for House 2.
For House 1:
- At 6 days, the cost is $97.50. Cost per day = \( \frac{97.50}{6} = 16.25\) per day.
- At 8 days, the cost is $130.00. Cost per day = \( \frac{130.00}{8} = 16.25\) per day.
- At 12 days, the cost is $195.00. Cost per day = \( \frac{195.00}{12} = 16.25\) per day.
Average Cost for House 1:
The cost per day remains consistent at $16.25 for House 1.
For House 2:
We will look at the graph to approximate the costs for House 2 on the x-axis for days 5, 10, and 15, etc. (which we see was provided as coordinates in the points plotted). The costs at these points are:
- At 5 days, about $75. Cost per day = \( \frac{75}{5} = 15\) per day.
- At 10 days, about $150. Cost per day = \( \frac{150}{10} = 15\) per day.
- At 15 days, about $225. Cost per day = \( \frac{225}{15} = 15\) per day.
- And similar calculations can be performed for other points if needed.
Average Cost for House 2:
The cost per day remains consistent at $15.00 for House 2.
Conclusion:
- House 1: $16.25 per day.
- House 2: $15.00 per day.
House 2 had the lowest accumulated electricity cost per day.
So, the answer is 2.