The range in which the usage vary is from 682.77 kilowatt-hours to 2867.11 kilowatt-hours.
Given the charge of electricity charge is 6.434 cents per kilowatt-hour.
Fixed customer charge = $7.81
Bill range = $51.74 to $192.28
Since every value is in $ , we will first convert cents to dollar
per kilowatt-hour charge will be $6.434/100 ( as $1 = 100 cents )
per kilowatt-hour charge = $ 0.06434 …(1)
Lets us first find the lower range of usage
Last year's lowest bill was $51.74 (including the customer charge)
So last year lowest bill = $51.74-$7.81 = $43.93 …(2)
We know that (per KWh charge)x(no. of KWh used)=Total bill. …(3)
Substituting the values from (1) & (2) we get
(0.06434)x(no. of KWh used)=$43.93
no. of KWh used=[tex]\frac{43.93}{0.06434} = 682.77 KWh[/tex]
Similarly we will solve for maximum KWh used
Lets us find the maximum range of usage
Last year's highest bill was $192.28 (including the customer charge)
So last year highest bill = $192.28-$7.81 = $184.47 …(4)
Substituting the value of (1) & (4) in (3) we get
(0.06434)x(no. of KWh used)=$184.47
no. of KWh used=[tex]\frac{184.47}{0.06434} =2867.11 KWh[/tex]
Therefore , the The range in which the usage vary is from 682.77 kilowatt-hours to 2867.11 kilowatt-hours.
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