Question

A researcher has saline solutions with concentrations of 3% and 7%. He wants to mix some of each solution to get 64 milliliters of solution with a 6% concentration. How many milliliter of each solution does he need to mix together?

Answer 1

Answer:

We have 3% and 7% solutions.  (We'll call these x and y)

We need 64 ml of 6% solution.

Setting up two equations:

A) x + y = 64 ml

B) .03x + .07y = (.06 * 64)

Multiplying A) by -.03

A) -.03x -.03y = -1.92  then adding this to B)

B) .03x + .07y = 3.84

.04y = 1.92

y = 1.92 / .04 = 48 ml of 7% solution

x = 16 ml of 3% solution

DOUBLE-CHECK

16 * .03 + 48 * .07 = 3.84 ml in 64ml

3.84 / 64 = .06 per cent!!

Source: https://www.1728.org/mixture.htm

Step-by-step explanation: