Mixture Problem

Question

 How many liters of a 15% NaCl solution should be mixed with 2 L of a 20% NaCl solution to obtain a 16% NaCl solution?

Answer 1

Volume*percentage=amount

 

Amount of salt in 15% solution + amount of salt in 20% solution=amount of salt in 16% solution.

 

0.15x=amount of salt in 15% solution

 

0.20*2 or 0.4=amount of salt in 2 liter solution

 

0.16*(x + 2)=amount of salt in 16% solution.  x+2 represents the combined volume of the mixture of the 15% and 20% solutions poured together.

 

0.15x + 0.4=0.16(x + 2)

 

Let the individual amounts equal the combined amount and then solve for x.

 

0.15x + 0.4=0.16x + 0.32

 

Subtract 0.15x from both sides

0.4=0.01x + 0.32

 

Subtract 0.32 from both sides

0.08=0.01x

 

Divide both sides by 0.01

 

8 L=x

 

Mix  8L of 15%solution with 2L of 20% solution.