Question 44

The electricity bill of a certain establishment is partly fixed and partly varies with the number of units of electricity consumed. When in a certain month 540 units are consumed, the bill is 1800. In another month 620 units are consumed and the bill is 2040. In yet another month 500 units are consumed. The bill for that month would be

Solution

let fixed unit be x and cost of each unit be y

540y + x =1800 .............(1)
620y + x = 2040.............(2)

Solving both the equation we will have y=3

Now placing y value in any of the equation give

x=180 (fixed value)

So now we will have

Bill = 180 +(500*3)

=1680

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