Question

Cost of production of each unit of electricity is 3 less than twice the total number of units produced. If the total cost of production is ₹ 20, find the number of units of electricity produced.

• A. 2.5
• B. 4
• C. 3
• D. 5

Answer 1

The correct option is B

4

Let the number of units of electricity produced be x.

Then, cost of production of each unit = ₹ $(2x-3)$

Total cost of production = ₹ $x(2x-3)$

$x(2x-3)=20$

$2x^2–3x–20=0$

$2x^2-8x+5x–20=0$

$2x(x-4)+5(x-4)=0$

$(2x+5)(x-4)=0$

$x$ = -2.5 or $x$ = 4

As number of units cannot be negative,

Number of electricity units produced = 4