Answer:

Outer surface area of Box  =  600 cm²

Step-by-step explanation:

a square piece of cardboard with sides 25 CM has a small square of side 2.5 CM cut out from each corner.

flaps are turned so as to make a box 2.5 cm deep.

=> Box is open from top with Depth/Height = 2.5 cm

and Length & Breadth = 25 - (2.5 + 2.5)  = 20 cm

Box Dimension = 20 * 20 * 2.5 cm

Outer surface area of Box  = 20 * 20  + 4  * 20 * 2.5

= 400 + 200

= 600 cm²

Other way

Area of Card board = 25 * 25 = 625 cm²

Areas of 4 square pieces cut = 4 * 2.5 * 2.5 = 25 cm²

Remaining area = 625 - 25 = 600 cm²

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