A scientist needs 10 litera of a 20% acid solution for an experiment but she has only 5% solution and a 40% solution. To the nearest tenth of a liter, how many liters of the 5% and the 40% solutions should she mix to get the solution she needs?
Let the number Liters of 5% solution needed =F
Then, the number of Liters of 40% solution needed =10 - F
0.05F + 0.4*[10 - F] =0.20 * 10, solve for F
F = 40 / 7 = 5 + 5/7 Liters of 5% solution.
10 - 5 5/7 = 4 + 2/7 Liters of 40% solution.
