Solution X contains 40% salt and 60% water by weights, Solution Y contains 25% salt and 75% water. If a mixture of X and Y contains 30% salt. What percent of the weight of this mixture is solution X?
A
10%
B
33.3%
C
40%
D
42.5%
Correct Answer: 33.3%
Let x g be the weight of solution X in 100 g of the mixture.Then, the weight of solution Y in 100 g of the mixture = (100 - x) gMass of salt in the mixture:x (40%) + (100 - x) (25%) = 100 (30%)40x + 2500 - 25x = 300015x = 500x = 33 1/3Hence, there are (33 1/3)% of solution X in the mixture.