How much water must be evaporated from 36 ounces of 8% salt solution to make 9% salt solution?

Question

cant seem to get the correct answer on this word problem!

Answer 1

8% salt is 92% water

9% salt is 91% water

0.92(36) - x = 0.91(36 - x)

33.12 - x = 32.76 - 0.91x

0.36 - x = - 0.91x

0.36 = 0.09x

4 = x

Answer 2

Original solution contains 8% salt.

Let x be the amount of water to be evaporated.

 

The resulting solution is contains 0.09(36-x) salt.

 

The equation is 0.08(36) - 0*X = 0.09(36-x)

 

    8(36)  = 9(36-x)  <--- multiplies everything by 100 to clear the decimals

 

   288 = 324 - 9x

 

   9x = 324 - 288

 

  9x = 36

  x = 4

 

So 4 ounces of pure high quality H20 must be evaporated.

 

 Check:  36*0.08 = 2.88 oz of salt in the original solution.

             4 oz of water evaporated but the salt remains.

             So the resulting solution of 32 oz contains 2.88 oz of salt.

             2.88 divided by 32 = 0.09 = 9%

 

 

The answer of 4 ounces water must be evaporated is proven to be correct.