Question

Annabel has 25 ounces of a 20% boric acid solution which she wishes to dilute to a 10% solution. How much water does she have to add in order to obtain the 10% solution?

Answer 1

this can be solve by establish an equation
let x be the amount of water to be added
y is the amount of the 10 % soultion formed

25 + x = y

then the other equation will be

25(0.80) + x = 0.90y

solving the equtions simultaneously
x = 25 ounces of water is need to dilute the solution to 10 % boric acid

Answer 2

Annabel will add 25 ounces of water in 20 % boric solution.

Explanation:

Annabel has 25 ounces of a 20% boric acid solution.

She wishes to dilute this solution to prepare a 10% solution.

We have to calculate the amount of water to be added to obtain 10% solution.

Let she adds x ounce of water with the 20% boric acid solution.

So the equation will be

Amount of 20% solution × strength = Amount of 10% solution × strength

25 ×
`(20)/(100)` = (25 + x) ×
`(10)/(100)`

25 × 0.20 = (25 + x)×0.10

5 = 2.5 + 0.10x

5 - 2.5 = 0.1x

2.5 = 0.1x

x =
`(2.5)/(0.1)`

x = 25 ounces

Therefore, Annabel will add 25 ml of water.