A cylindrical glass jar of internal diameter and height is filled with loose rice grains

MATHEMATICS · Subjective · GCSE · Mathematics · Number · Number

Problem

A cylindrical glass jar of internal diameter

10\,\text{cm}

and height

20\,\text{cm}

is filled with loose rice grains. Assume each grain can be approximated by a cylinder of length

6\,\text{mm}

and diameter

2\,\text{mm}

, and that the grains occupy about

60\%

of the jar’s volume because of the gaps between them. Estimate, to the nearest order of magnitude, how many grains of rice the jar contains.