charlie has 80 ml of a 15% acid solution how much of a 20% acid slolution must be added to create a solution that is 18% acid.
Let x be the number of ml that must be added. The amount of acid contained in the mix can be written two ways, and is:
0.15*80 + 0.20x = 0.18*(80 + x)
Solve for x
12 + 0.20x = 14.4 + 0.18x
0.02x = 2.4
x = 120 ml
To solve this problem, we'll need to set up an equation based on the given information.
Let's assume that the amount of the 20% acid solution to be added is x ml.
The amount of acid in the 15% solution is 80 ml * 15% = (80 * 15) / 100 = 12 ml.
The amount of acid in the 20% solution to be added is x ml * 20% = (x * 20) / 100 = 0.2x ml.
The total amount of acid in the final solution should be (80 + x) ml * 18% = ((80 + x) * 18) / 100 = 0.18(80 + x) ml.
According to the problem, the amount of acid in the 15% solution plus the amount of acid in the 20% solution should be equal to the amount of acid in the final solution. So, we can set up the equation:
12 ml + 0.2x ml = 0.18(80 + x) ml
Let's solve this equation to find the value of x:
12 + 0.2x = 14.4 + 0.18x
0.2x - 0.18x = 14.4 - 12
0.02x = 2.4
x = 2.4 / 0.02
x = 120
Therefore, Charlie needs to add 120 ml of the 20% acid solution to create a solution that is 18% acid.