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AP EAMCET · Maths · Application of Derivatives

If a running track of 500 ft . is to be laid out enclosing a playground, the shape of which is a rectangle with a semicircle at each end, then the length of the rectangular portion such that the area of the rectangular portion is to be maximum is (in feet).

  1. A 100
  2. B 125
  3. C 150
  4. D 200
Verified Solution

Answer & Solution

Correct Answer

(B) 125

Step-by-step Solution

Detailed explanation

Perimeter of track \(=500 \mathrm{ft}\). \(\Rightarrow 500=2 x+2 \pi r\) So, area of rectangular portion \(=x \times 2 r=2 r(250-\pi \mathrm{r})\)…