How much of a 30% solution do you need to add to 280ml of water to make it a 4% solution?

Explanation:

They don't specify what the chemical solution is, but let's say you had a mix of water and gold particles. If you had x ml of this chemical solution, then 0.30x of that is pure gold.

Dividing the amount of pure gold (0.30x) over the amount of solution (x) leads to 30%, so,

(0.30x)/x = 0.30

We want to add 280 ml of water. This will increase the amount of total solution (x) but will not change the amount of pure gold (0.30x)

So the fraction (0.30x)/x becomes (0.30x)/(x+280). We want this to be equal to 0.04 which is the 4% we're after.

We therefore need to solve this equation (0.30x)/(x+280) = 0.04

Let's do so

(0.30x)/(x+280) = 0.04

0.30x = 0.04(x+280)

0.30x = 0.04(x)+0.04(280)

0.30x = 0.04x+11.2

0.30x-0.04x = 11.2

0.26x = 11.2

x = 11.2/0.26

x = 43.076923076923 which is approximate

x = 43.0769 rounding to 4 decimal places

You can round however you want. I would ask your teacher about rounding instructions.

answer: its the third option.

step-by-step explanation:

i just took the test.