In what report should the solutions of the salt 55% and 20% be mixed to obtain a 40% salt solution.

Answer 1

If you've ever learned about alligation, you can use that here to solve this problem.

Put what you have on the left and what you want in the middle. Then subtract diagonally to get parts needed.

HAVE.......WANT..........PARTS

55%................................20....

..................40.........................

20%................................15....

So you would need to mix 20 parts of the 55% solution with 15 parts of the 20% solution.

The ratio of parts would thus be 20:15 or 4:3.

Hope this helps.

Answer 2

.55x +.2y = .4(x+y)= .4x +.4y

.15x = .2y

15x =20y

3x = 4y

in ratios of x:y = 4:3

4 parts 55% for 3 parts 20% to yield 4+3 = 7 parts 40%

4(.55) +3(.20)

= 2.2 +.6

= 2.8

7(.4)

= 2.8

another way to solve the problem (or to check the answer)

is

55-40 =15

40-20 = 20

55 is closer to 40, so you know you need more of 55 than of 20

20/15 = 4/3, 4 parts 55%, 3 parts 20%