How many liters of a solution that is 15 percent water by volume have to be added to 3 litters of a solution that is 30 percent water by volume to creat a solution that is 20 percent water by volume? gees, I just get confused. please explain that on earth is talking about???
2007-03-19 16:41:29 · 4 answers · asked by liangjizong22 1 in Science & Mathematics ➔ Mathematics
let x = # of liters in 15% solution
let 3 = # of liters in 30% solution ("added to 3 litters ")
.15x + .30*3 = .20(x+3)
.15x + .9 = .20x + .60
.90 - .60 = .20x - .15x
.3 = .05x
.3/.05 = x
x = 6
answer - 6 liters
2007-03-19 16:50:37 · answer #1 · answered by Bill F 6 · 0⤊ 0⤋
you already have 3 liters of 30%
want to add.15% until the solution is 20&
so
3 X .30 = .90 (that is the 3 liters of 30%)
.15x (this is the x liters of 15%)
when we add both of these together will get 20% solution that is made of the total of the 3 liters and the x liters
.90 + .15x = .20(3 + x)
.90 + .15x = .60 + .20x
.30 = .05x
6 = x
So would add 6 liters
2007-03-19 23:56:32 · answer #2 · answered by watanake 4 · 0⤊ 0⤋
Let x litres of a solution of 15% water must be added to 3 litres of 30% solution.
15% of x+30%of 3 = 20%of (x+3)
15% 0f(x+6) = 20% of (x+3)
so x=6 litre
2007-03-20 04:59:06 · answer #3 · answered by prateeksha j 1 · 0⤊ 0⤋
If x is the amount to add, then
x(15/100) + 3(30/100) = (3+x)(20/100)
15x + 90 = 60 + 20x
5x = 30
x = 6
2007-03-19 23:52:58 · answer #4 · answered by Anonymous · 0⤊ 0⤋