What is the monthly electricity bill for a house with 7 rooms consuming 300 units ?

Consider the following for the next two (02) items that follow : The total monthly electricity bill for a house consists of the sum of two parts, one part is proportional to number of rooms and the other part is proportional to number of units consumed. ₹ 400 is the monthly electricity bill for a house with 8 rooms and consuming 240 units and ₹ 320 is the monthly electricity bill for a house with 6 rooms and consuming 200 units.

  1. A. 500
  2. B. 440
  3. C. 340
  4. D. 300

Correct Answer: B. 440

Explanation

Using the formula derived in the previous question: Bill = 20m + n. For m=7 rooms and n=300 units, the bill is 20(7) + 300 = 140 + 300 = 440.

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