The figure is not drawn to scale. It shows the net of a solid. It is made up of 4 identical rectangles and 2 identical squares. Line L is 30 cm long and Line M is 21 cm long.
- Find the volume of the solid.
- This solid is a cardboard carton containing small boxes of mochi balls. Each box of mochi balls is 3 cm by 2 cm by 2 cm. If all these small boxes of mochi balls in the carton occupy more than 60% of the carton's volume, what is the minimum number of small boxes of mochi balls in the carton?
(a)
Breadth of the cuboid
= 21 ÷ 3
= 7 cm
Breadth of two squares
= Breadth x 2
= 7 x 2
= 14 cm
Length of the cuboid
= (30 - 14) ÷ 2
= 8 cm
Volume of the cuboid
= 8 x 7 x 7
= 392 cm
3 (b)
Volume of one box of mochi balls
= 3 x 2 x 2
= 12 cm
3 Volume of space occupied
= 392 x 60%
= 235.2 cm
3 Estimated number of small boxes
= 235.2 ÷ 12
≈ 19.6
Minimum number of small boxes to occupy more than 60% of the carton
= 19 + 1
= 20
Answer(s): (a) 392 cm
3; (b) 20