The figure shows a plastic cuboid that measures 128 cm by 21 cm by 21 cm.
- Find the maximum number of 5-cm cubes that can be cut from the plastic cuboid.
- Find the total surface area of the L-shaped block after cutting.
(a)
Number of cubes along the length
= 128 ÷ 5
= 25 r 3
Breath = Height
Number of cubes along the breadth or height
= 21 ÷ 5
= 4 r 1
Maximum number of 5 cm cubes
= 25 x 4 x 4
= 400
(b)
Area of the 2 squares
= 2 x 21 x 21
= 882 cm
2 Area of the top and bottom bases
= 2 x 128 x 21
= 5376 cm
2 Area of 1 L-shaped side
= 128 x 1 + (21 - 1) x 3
= 128 + 60
= 188 cm
2Area of 2 L-shaped sides
= 2 x 188
= 376 cm
2 Total surface area
= 5376 + 882 + 376
= 6634 cm
2 Answer(s): (a) 400; (b) 6634 cm
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