Question 1190772: In 2014, TTEC had the following rate schedule for electricity usage for residential purposes;
Monthly service charge $200.00 Per KWh charge:
1st 600 KWh: $1.25/KWh
Over 600 KWh: $2.51/KWh
(i) What is the charge for using 599 KWh in a month? [2]
(ii) What is the charge for using 2600 KWh in a month? [3]
(iii) If C is the monthly charge for x KWh, develop a model relating the monthly charge and kilowatt-hours used. That is, express C as a function of x. [4]
Answer by Theo(13342)   (Show Source):
You can put this solution on YOUR website! i understand this as:
monthly charge is 200.
this is paid regardless of the number of kilowatt hours used.
the per kilowatt charge is 1.25 for the first 600 kilowatt hours and 2.51 per kilowatt hour for any kilowatt hours over 600.
with that understanding.....
if you used 599 kilowatt hours in a month, then your monthly charge would be 200 + 1.25 * 599 = 948.75
if you used 2600 kilowatt hours in a month, then your monthly charge would be 200 + 1.25 * 600 + 2.51 * (2600 - 600) = 5719.
the general equation would be a piecemeal function that would be:
c(x) = 200 + 1.25 * x for x <= 600.
c(x) = 950 + 2.51 * (x - 600) for x > 600.
the function would be applied as follows:
if x <= 600, then the first function would be applied.
if x > 600, then the second function would be applied.
when 599 kilowatt hours were used, the first function would be applied to get 200 + 1.25 * 599 = 948.75
when 2600 kilowatt hours were used, the second function would be applied to get 950 + 2.51 * (2600 - 600) = 5970.
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