Question

The mass of a grain is sand is 10^-3 grams. About how many grains of sand are in a bag of sand that weighs 2.8 grams?

Answer 1

we can solve this problem by the rule of three.

1 grain-----------------------10⁻³ g
x-------------------------------2.8 g

x=(1 grain * 2.8 g)/10⁻³ g=(1 grain * 2.8 g * 10³)/g=2800 grains.

answer: there are 2800 grains of sands