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Mathematics

Three electricity plans are available in a certain county. The monthly usage and corresponding charges for that usage for three households, each using a different plan is shown below. Which plan, if any, has the lowest cost per kilowatt-hour (kWh)?

A.Plan A
B.Plan B
C.Plan C
D.The plans all cost the same amount per kilowatt-hour.

答案和解析

答案：A

解析：

Choice A is correct. Find the cost per kilowatt-hour for each of the three plans.

For Plan A:
$106.50/930kWh≈$0.11per kWh
For Plan B:
$110.70/900kWh≈$0.12per kWh
For Plan C:
$115.20/810kWh≈$0.14per kWh

Plan A has the lowest cost per kilowatt-hour.