Should I use ratio, rate, fold, or increase?

Question

The amounts of ingredients a, b and c in A (solution) were 1, 2 and 3, respectively. I have prepared B, C and D solutions with the ingredients as below.

The amounts were multiplied by 1.5 for solution B, resulting in a,b,c having the amounts of 1.5, 3, 4.5, respectively. The, the amounts were multiplied by 3 for solution C, resulting in a,b,c having the amounts of 3, 6, 9 respectively. Also, the amounts were multiplied by 0.5 for solution D, resulting in a,b,c having the amounts of 0.5, 1, 1.5 respectively.

As above, based on the amounts of ingredients of solution A, the amounts of the ingredients of B,C,D were determined by multiplying a specific number to A.

Then, how can I express these changes collectively regarding the preparation of solutions B,C and D?

How about:

1. B, C and D solutions were prepared according to the recipe (composition?) in which the amount of each ingredient was increased or decreased at a specific rate as compared to A

2. B, C and D solutions were prepared according to the recipe in which the amount of each ingredient was changed with a specific fold increase or decrease as compared to A

3. B, C and D solutions were prepared according to the recipe in which the amount of each ingredient was changed by (with? according to?) a specific ratio in relation to A

I would like to know your better answers as well as your opinions.

Answer 1

Four solutions were prepared using a 1:2:3 ratio of ingredients a, b, and c respectively. Solution A had 6 units (1 of a, 2 of b, and 3 of c). Solution B had 9 units, solution C had 18 units, and solution D had 3 units.

Answer 2

Four different volumes(?), 0.5, 1, 2 and 3 units(?), were prepared of the solution(?) while keeping the components(?), a,b and c in the same ratio of 1:2:3.

It isn't clear if you making bread, mixing cocktails, or making some sort of chemistry solution. For instance recipe sounds like cooking, not chemistry. Cooks generally talk about mixtures, not solutions.

Answer 3

The answer depends to some degree on the context. If you're writing in a formal style, use the word "ratio" or "proportion":

The ratio of ingredients a, b, and c was held constant.
The amounts of ingredients b, c, and d were held in constant proportion to ingredient a.

For a more informal style, use the word "parts". This is especially common with recipes:

Combine 1 part A, 2 parts B, and 3 parts C.

For the multiplier itself, use "factor":

The amount of ingredient a in B was a factor of 1.5 larger than the amount in A.

You could also replace "larger than" with "times" if you wanted, to make it even more clear you're talking about multiplication.

Answer 4

The solutions were prepared according to the recipe, which called for the total concentrations be increased by a fixed ratio at each step, such that b = 1.5a and c = 2a. You could also say "such that the final total concentrations were 1:1.5:2.