Answer:
The answer is 7.72 grains, this means between 7 and 8 grains.
Explanation:
First you must have the mass in the same units, that is in g or mg.
In this case the unit chosen is g. So they will convert the mass that contains a grain to g. For that you use the following Rule of Three:
If 1 mg represents 0.001 g, then how many grams are 64.8 mg?
\(\frac{64.8 mg* 0.001 g}{1 mg} =0.0648 g\)
Now, to calculate how many grains represent 0.5 g, a new Rule of Three can be used:
If 1 grain represents 0.0648 g, then how many grains are 0,5 g?
\(\frac{0.5 g*1 grain}{0.0648 g} =7.72 grains\)
So the answer is 7.72 grains.
