Calculating new value in increased serving size

Question

This is probably going to sound like a very stupid question but I'm more of a designer than a maths person unfortunately.

I'm just trying to work out how I'd get a new weight of an ingredient for a serving size when I know that current weight for a serving.

So I have 3000mg of Ingredient "A" in a 5.1gram serving. I need to work out how much I have in an 8gram serving.

I thought it was just a case of (3000 / x) * 8 = value But obviously the more I increase x the less the value is.

As i said probably a really easy question but I'm struggling :)

Answer 1

There are a couple different ways to set it up. Here's one. $$\dfrac{3000 \text{ mg}}{5.1 \text{ gram}} = \dfrac{x \text{ mg}}{8 \text{ gram}}$$ Solve for $x$ by multiplying both sides by $8$. $$x = \frac{3000}{5.1} \cdot 8 \approx 4705.88 \text{ mg}$$

Answer 2

The proportions must stay the same, so

$$ \frac{x}{3000} = \frac{8}{5.1} . $$

Answer 3

Suppose you have x miligram of ingredient in 8 gram of food, then using law of proportions:

$$\frac{x}{8} = \frac{3000}{5.1} $$ $$\frac{x}{3000} = \frac{8}{5.1} $$ From here $x$ comes out to be $4705.8823$