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Math help needed!

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Ok so it’s late Friday afternoon and my brain won’t function anymore, so I need the help of the Math Wizards out there.

I need to work out how to divide the electricity amount due between 2 sets of tenants, where the meter was not read by Eskom for a year.

The reading is for 276 days.

Karin lived there for 199 days.

Mel lived there for 77 days.

Mel used twice as many units per day as Karin did.

Total units used is 4816.

Total cost is R8 463.60.

(Average cost per day is R30.66) (might not be needed to calculate)

(Average units per day is 17.45) (might not be needed to calculate)

How much does Karin owe and how much does Mel owe?

Please include your formula / process in your answer.


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DJ has a fair question.


Assuming that there's no overlap, here is my best estimation.


Because Mel used twice as many units, that's equivalent to two people living there. Call him Mel1 and Mel2.


Karin = 199 days

Mel1 = 77 days

Mel2 = 77 days


Altogether, that's 353 days of usage.


4816 units divided by 353 days equals 13.643 units per day. 


R8 463.60 divided by 4816 units equals R1.757 per unit.


Karin: 13.643 units per day times 199 days * R1.757 per unit equals R4 770.18


Mel: 13.643 units per day times (77 days plus 77 days) * R1.757 per unit equals R3 691.50


Together, the two bills equals R8 461.68, which is within 2 of your listed total, the difference due to rounding. You could either eat that difference, or split it between the two. Calculated out, Karin's portion is 56.4% of the total, whereas Mel's portion is 43.6%. 

Edited by JamesBrown
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Just the thought of math makes my head spin.

However, I’ll volunteer to chair a meeting that includes a judge, two lawyers, social workers, mental health, child protective services, the school district, probation officers, and a group home.




Edited by Ryrin
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