
William W. answered 07/20/22
Math and science made easy - learn from a retired engineer
Break even points are when the cost equals the sales price. Obviously, you aren't going to make any money if that happens but it is necessary to understand so that you can determine the optimum number of units to manufacture.
Total cost = fixed cost + variable cost
You are told the fixed cost. To determine the variable cost you take the "variable cost per unit" and multiply it by the number of units, so (140 + 0.04x)(x) = 140x + 0.04x2
Total cost = 15000 + 140x + 0.04x2
Your selling price is (300 - 0.06x) multiplied by the number of units so (300 - 0.06x)(x) = 300x - 0.06x2
Break even means cost = sales therefore:
15000 + 140x + 0.04x2 = 300x - 0.06x2
To solve a quadratic, move everything to one side setting the quadratic equal to zero:
15000 + 140x + 0.04x2 - 300x + 0.06x2 = 0 and combine like terms to get:
0.10x2 - 160x + 15000 = 0
You can now either factor the quadratic or use the quadratic formula. I'll choose to factor:
Multiply both sides by 10 to get:
x2 - 1600x + 150000 = 0
(x - 1500)(x - 100) = 0
Set each factor equal to zero:
x - 1500 = 0 meaning x = 1500 and x - 100 = 0 meaning x = 100
So, the break even points are when you make 100 units and when you make 1500 units. When you manufacture less than 100 units, your cost will be more than your revenue (so you'll lose money). If you make more than 1500 units, again your cost will be more than your revenue. Only when you manufacture between 100 and 1500 units will you make a profit.