Answer:
A. $1,710
B. Yes, probably.
Step-by-step explanation:
Assuming that a 10% decrease in energy use leads to a 10% decrease in the electric bill:
We'll want to find the value which is 10% less than the original value, i.e., the bill cost which is 90% of the original bill.
90% = 0.9
Since the original bill was $1900, we can just multiply 1900 by 0.9:
Answer: A bill of $1,710 would equal a 10% decrease.
Since $1,672 is less than that, then they have decreased their energy use by more than 10% which is likely a success.
Answer: Yes, probably.