How many kilograms of gold do you need to add to 1.2 kilograms of silver to get an electr with a 30% silver content?

If the electrolyte contains 30% silver, then the gold content will be:

100% – 30% = 70%.

Let the total mass of gold in the electrolyte be X kilogram, then the silver in the electrolyte, by condition, is 1.2 kilograms. Let’s compose and solve the resulting proportion:

1.2 kilograms – 30%;

X kilogram – 70%;

1.2 * 70 = 30 * X;

84 = 30X;

X = 84: 30;

X = 2.8.

Thus, in order for the silver content in the electrolyte to be equal to 30%, 2.8 kilograms of gold must be added.

Answer: 2.8 kilograms.