All Exams Test series for 1 year @ ₹349 only
Question

The electricity bill of a certain establishment is partly fixed and partly variable depending on the number of units of electricity consumed. In a certain month when 540 units were consumed, the bill was ₹1,800. In another month when 620 units were consumed, the bill was ₹2,040. If in a month 500 units are consumed, then the bill for that month will be:

This question was previously asked in
RRB NTPC 2019 CBT 1 Question Paper (8-Mar-2021) (Shift 2)
The correct answer is
₹1,680

The problem involves calculating an electricity bill composed of a fixed charge and a variable charge based on electricity units consumed. We need to determine the fixed and variable rates from the given data and then calculate the bill for a specific consumption.

Formulating Equations for Electricity Bill

Let F represent the fixed charge (in ₹) and V represent the variable charge per unit (in ₹/unit). The total bill (B) is calculated using the formula: B = F + V × U, where U is the number of units consumed.

From the given information:

  • Month 1: 540 units consumed, Bill = ₹1,800. This gives the equation:
    $1800 = F + 540V$ (Equation 1)
  • Month 2: 620 units consumed, Bill = ₹2,040. This gives the equation:
    $2040 = F + 620V$ (Equation 2)

Calculating Variable Charge per Unit (V)

To find the variable charge per unit (V), we subtract Equation 1 from Equation 2:

$(2040 - 1800) = (F + 620V) - (F + 540V)$
$240 = 620V - 540V$
$240 = 80V$

Now, solve for V:

$V = \frac{240}{80}$
$V = 3$

So, the variable charge is ₹3 per unit.

Calculating Fixed Charge (F)

Substitute the value of V (₹3) back into Equation 1 to find the fixed charge (F):

$1800 = F + 540 \times 3$
$1800 = F + 1620$
$F = 1800 - 1620$
$F = 180$

The fixed charge is ₹180.

Calculating Bill for 500 Units

Now, calculate the bill for a month when 500 units are consumed using the determined values of F and V:

$B = F + V \times U$
$B = 180 + 3 \times 500$
$B = 180 + 1500$
$B = 1680$

Therefore, the bill for 500 units consumed will be ₹1,680.

Was this answer helpful?

Similar Questions

  1. The cost of 7 pens and 8 pencils is ₹230. If the cost of a pen decreases by ₹1 and the cost of a pencil increases by ₹7, then the cost of 14 pens and 4 pencils is ₹150. What is the original cost of 8 pens and 8 pencils?
  2. The cost of 2 pens and 15 pencils is ₹286. If the cost of a pen decreases by ₹4 and the cost of a pencil increases by ₹2, then the cost of 17 pens and 3 pencils is ₹128. What is the original cost of 11 pens and 8 pencils?
  3. The cost of 10 pencils and 12 pens is ₹150. What is the cost of 30 pencils and 36 pens?
  4. If 33 is the sum of two numbers and 13 is their difference, then find the largest number.
  5. 2 chairs and 1 table cost ₹880, while 1 chair and 2 tables cost ₹980. Find the cost of each.
  6. Rakesh has coins in the denominations of only ₹2 and ₹5 with him. If the total number of coins that he has is 60 and the amount of money with him is ₹240, then find the number of ₹2 and ₹5 coins respectively.
  7. If $2x - 3y = 7$ and $\frac{x}{x+y} = \frac{5}{6}$, then what is the value of $x - y$?
  8. If $2x - 3y = -1$ and $\frac{x}{x+y} = \frac{7}{12}$, then the value of $2xy$ is:

  9. If the system of equation $3x - 2y = 8$, $2ax + (a-b)y = 48$ has infinitely many solutions then:
  10. If $2x + 3y = 23$ and $x = 4$, then what is the value of $y$?

Important Questions from Linear Equation in 2 Variable

  1. What is the solution of the following equations ?

    2x + 3y = 12 and 3x − 2y = 5

  2. Two positive numbers differ by 1280. When the greater number is divided by the smaller number, the quotient is 7 and the remainder is 50. The greater number is:

  3. When 5 children from class A join class B, the number of children in both classes is the same. If 25 children from B, join A, then the number of children in A becomes double the number of children in B. The ratio of the number of children in A to those in B is:

  4. If (x + 6y) = 8, and xy = 2, where x > 0, what is the value of (x 3+ 216y 3)?

  5. If 8k 6+ 15k 3– 2 = 0, then the positive value of \(\left( {{\rm{k}}\,{\rm{ + }}\,\frac{1}{{\rm{k}}}} \right)\)  is :

Need Expert Advice?
Upcoming Exams
RRB ALP
July 28, 2026
RRB Group D
August 03, 2026
Test Series
RRB NTPC img
Railways
RRB NTPC Under Graduate 2026 New Mock Test Series
1459 Tests 2 Tests Free
212 Attempts
4.3(512)
English, Hindi, Telugu +7 More

Start Your Preparation with Prepp Mobile App

Download the app from Google Play & App Store
Download the app from Google Play & App Store
Prepp Mobile App