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Age 14 to 16
Challenge Level
The average dimension for each of the following objects is given in the table below:
| Length | Cross - Sectional Area | Volume | Modelling by which solid? | |
| Mitochondria | 1 $\mu$m | 0.79 $\mu$m$^2$ | 0.79 $\mu$m$^3$ | Cylinder |
| Arabis voch pollen | 30 $\mu$m | 706.9 $\mu$m$^2$ | 14137 $\mu$m$^3$ | Sphere |
| Ring stage of Plasmodium falciparum | 1.5 $\mu$m | 0.79 $\mu$m$^2$ | 0.03 $\mu$m$^3$ | Ring |
| Tuberculosis bacterium | 2 $\mu$m | 0.12 $\mu$m$^2$ | 0.24 $\mu$m$^3$ | Cylinder |
| Human red blood cell | 8 $\mu$m | 50 $\mu$m$^2$ | 100 $\mu$m$^3$ | Disc |
| Human nerve cell | 2 $\mu$m | 3 $\mu$m$^2$ | 0.3 $\mu$m$^3$ | Disc |
| The eye of a needle | 1 mm | 1 mm$^2$ | 0.1 mm$^3$ | Cuboid |
| Cat hair | 3 cm | 0.3 mm$^2$ | 9 mm$^3$ | Cylinder |
| Snowflake crystal | 1 cm | 0.79 cm$^2$ | 0.17 cm$^3$ | Sphere |
Therefore, we can roughly rank these objects by length, volume and cross - sectional area.
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NRICH is part of the family of activities in the Millennium Mathematics Project.
NRICH is part of the family of activities in the Millennium Mathematics Project.