【官方】SAT数学每日一题附答案和解析(2018年2月7日)

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每日一练：数学

Math: Calculator Permitted

Read the following question and then select the best answer.

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 left parenthesis text kWh end text right parenthesis?

Plan A

Plan B

Plan C

Kilowatts used

930 kWh

900 kWh

810 kWh

Monthly charge

$106.50

$110.70

$115.20

Select an Answer

A.Plan A

B.Plan B

C.Plan C

D.The plans all cost the same amount per kilowatt-hour.

答案及解析：A

EXPLANATION

For Plan A: $ 106.50/930 kWh≈$0.11per kWh

For Plan B: $ 110.70/900 kWh≈$0.12per kWh

For Plan C: $ 115.20/ 810 kWh≈$0.14per kWh