Question

A scientist mixes water (containing no salt) with a solution that contains 45% salt. she wants to obtain 180 ounces of a mixture that is 30% salt. how many ounces of water and how many ounces of the 45% salt solution should she use?

Answer 1

Water: 40 ounces

Salt solution: 140 ounces

Answer 2

Solution contains 45% salt
She wants to obtain 180 ounces of a mixture that is 30% salt
Ounces of water with 45% salt solution = ?
30% = 0.3 and 45% = 0.45
Let V is the volume of water to be mixed in ounces, then the volume of the 45% salt solution needed is 180-V
The balanced equation for the mass of salt is
0.45 x (180-V) = 0.3 x 180
81 – 0.45V = 54
0.45V = 81-54
0.45V = 27
V = 60
So, 60 ounces of water is needed