You need a 60% alcohol solution. On hand, you have a 325 mL of a 5% alcohol mixture. You also have 85% alcohol mixture. How much of the 85% mixture will you need to add to obtain the desired solution?

Answer 1

85-60 = 25

60-5 = 45

45/25 =9/5 = 2.2

2.4 times as much 85% as 5%

x/325 = 2.2

x= 715 mL of 85%

.05(325) + .85x = .6(325+x)

16.25 + .85x = 195+.6x

.25x = 178.75

x = 178.75/.25 = 715 mL