You need a 10% alcohol solution. On hand, you have a 935 mL of a 5% alcohol mixture. You also have 95% alcohol mixture.

Question

How much of the 95% mixture will you need to add to obtain the desired solution?

Answer 1

935(.05) + x(.95) = (935+x)(.10)

.95x -.10x = (935).10 - 935(.05)

.85x = .05(935) = 93.5/2 = 46.75

x = 46.75/.85 = 55 mL of 95%

935+55 = 990 mL of 10%

check the answer

935(.05) + 55(.95)

= 46.75 + 52.25

= 99

= (935+55).1 = 990(.1)=99

10-5 = 5

95-10 = 85

85/5 = 17

935/55 = 17