To find out which house had the lowest cost per day, we first need to calculate the cost per day for both houses based on the data provided.
For House 1 (from the table):
- 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.
Thus, the cost per day for House 1 is consistently $16.25.
For House 2 (from the graph):
We can observe the costs at specific days from the graph points:
- At 10 days, the cost is $150.00. Cost per day = \( \frac{150.00}{10} \) = $15.00 per day.
- At 15 days, the cost is $225.00. Cost per day = \( \frac{225.00}{15} \) = $15.00 per day.
- At 20 days, the cost is $300.00. Cost per day = \( \frac{300.00}{20} \) = $15.00 per day.
- At 25 days, the cost is $375.00. Cost per day = \( \frac{375.00}{25} \) = $15.00 per day.
- At 30 days, the cost is $450.00. Cost per day = \( \frac{450.00}{30} \) = $15.00 per day.
Thus, the cost per day for House 2 is consistently $15.00.
Comparison:
- House 1 cost per day: $16.25
- House 2 cost per day: $15.00
Since $15.00 (House 2) is less than $16.25 (House 1), House 2 had the lowest cost per day.
So, the answer is: 2 (House 2 had the lowest accumulated electricity cost per day.)