Question

the diameter of two silver discs are in thr ratio 2:3 what will be the ratio of their areas

Answer 1

As radius is 1/2 diameter, the ratio of the radii of the two circles will also be 2:3.

Let the radii of two circles be 2x and 3x respectively.

Area of first circle:
$\pi {(2x)}^{2}$
Area of second circle:
$\pi {(3x)}^{2}$
Ratio of the area of both circles:
$\frac{\pi {(2x)}^{2} }{\pi {(3x)}^{2} } \\ \\ = \frac{4 {x}^{2} }{ {9x}^{2} } \\ \\ = \frac{4}{9}$
Hence ,the ratio of areas of two circular discs are 4:9.
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Answer 2

see the picture given above