Question

There is a square park in the society. The management wants to put a circular fountain at the centre of the park with diameter 14 m. The remaining area is to be covered with grass. If the cost of laying grass is ₹ 20 per $m^2$ and the cost of constructing the fountain is 10 per $m^2$ . Find the length of the field if the total cost incurred is ₹ 6460 .( Use π = 22/7)

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Answer 1

Diameter of a circular fountain= 14 m, so radius = 7 m.

Let the length of the square be 'a'.

Total cost = cost of fountain + cost of grass.

Hence, ₹ 6460 = (area of fountain x cost per $m^2$) + (area of square park -area of circular fountain) x (cost for grass per $m^2$)

6460 = ($\pi (7{)}^2\times 10)+((a^2-\pi (7{)}^2\times 20)$

6460 = $(154\times 10)+(a^2-154)\times 20$

6460 =1540+($a^2-154)\times 20$

a = 20 m.