To determine how much of the 10% saline solution the nurse should use, let's denote the amount of the 10% solution as x cc.
Given:
Volume of the 70% saline solution: 60 cc
Concentration of the 70% saline solution: 70%
Concentration of the 10% saline solution: 10%
Desired concentration of the resulting solution: 35%
To find the amount of the 10% solution, we can set up an equation based on the principle of the concentration of solutions:
(0.7 * 60 + 0.1 * x) / (60 + x) = 0.35
In this equation, we multiply the concentration of each solution by its corresponding volume and divide by the total volume of the resulting solution.
Simplifying the equation, we get:
(42 + 0.1x) / (60 + x) = 0.35
Cross-multiplying, we have:
42 + 0.1x = 0.35 * (60 + x)
Expanding the right side of the equation, we get:
42 + 0.1x = 21 + 0.35x
Moving all the x terms to one side, we have:
0.35x - 0.1x = 42 - 21
0.25x = 21
Dividing both sides by 0.25, we get:
x = 21 / 0.25
x = 84
Therefore, the nurse should use 84 cc of the 10% saline solution to mix with the 60 cc of the 70% saline solution to produce a 35% saline solution.