The cost of making $x$ units is $C(x) = 100 + 12x + x^{2}$ rupees. Using the marginal cost at $x = 10$ , estimate the cost of making the 11th unit.

₹12Correct answerYour answer₹22Correct answerYour answer₹32Correct answerYour answer₹320Correct answerYour answer

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CorrectNot quiteAnswer C

Correct answer: C

$C'(x) = 12 + 2x$ , so $C'(10) = 32$ .
The 11th unit costs about ₹32. (Exactly, $C(11) - C(10) = 353 - 320 = 33$ ; the marginal cost is the quick estimate.)

Worth noting

₹320 is the cost of all 10 units, $C(10)$ .

Ten questions from Rate of Change, Marginal Cost & Revenue, at your own pace.

Ten questions from Rate of Change, Marginal Cost & Revenue, at your own pace.

The cost of making xxx units is C(x)=100+12x+x2C(x) = 100 + 12x + x^{2}C(x)=100+12x+x2 rupees. Using the marginal cost at x=10x = 10x=10, estimate the cost of making the 11th unit.