Question 1155823
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Answer: <font color=red>1:6.25</font>


Imagine we had 2 squares. One square is 1 by 1, so its area is 1*1 = 1 suare unit. The second square is 2.5 by 2.5, so its area is 2.5*2.5 = 6.25 square units. 


The ratio of the side lengths is 1:2.5, meaning that the second square's side length is 2.5 times longer than the first square's side length. 


The ratio of the areas is 1:6.25, meaning the second square's area is 6.25 times that of the first square's area.


The surface area in general follows this idea, so the ratio of surface areas of the two cones is 1:6.25
The same idea applies to the lateral surface areas as well. This is because we can unfold the outer surface (think of peeling off a sticker label) to form the geometric net, which is just a flat 2D shape. That shape has an area, leading to the surface area.
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