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A telephone company in a town has 500 subscribers on its list and collects fixed charges of Rs 300/- per subscriber per year. The company proposes to increase the annual subscription - Mathematics

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प्रश्न

A telephone company in a town has 500 subscribers on its list and collects fixed charges of Rs 300/- per subscriber per year. The company proposes to increase the annual subscription and it is believed that for every increase of Re 1/- one subscriber will discontinue the service. Find what increase will bring maximum profit?

योग
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उत्तर

Let us consider that the company increases the annual subscription by ₹ x.

So, x is the number of subscribers who discontinue the services.

∴ Total revenue, R(x) = (500 – x)(300 + x)

= 150000 + 500x – 300x – x2

= – x2 + 200x + 150000

Differentiating both sides w.r.t. x,

We get R'(x) = – 2x + 200

For local maxima and local minima, R'(x) = 0

– 2x + 200 = 0

⇒ x = 100

R"(x) = – 2 < 0 Maxima

So, R(x) is maximum at x = 100

Hence, in order to get maximum profit, the company should increase its annual subscription by ₹  100.

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अध्याय 6: Application Of Derivatives - Exercise [पृष्ठ १३७]

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एनसीईआरटी एक्झांप्लर Mathematics [English] Class 12
अध्याय 6 Application Of Derivatives
Exercise | Q 27 | पृष्ठ १३७

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