You need 1050 mL of a 50% alcohol solution. On hand, you have a 25% alcohol mixture. How much of the 25% alcohol mixture and pure alcohol will you need to obtain the desired solution?

Question

You need 1050 mL of a 50% alcohol solution. On hand, you have a 25% alcohol mixture. How much of the 25% alcohol mixture and pure alcohol will you need to obtain the desired solution?

Answer 1

x +(1050-x).25= 1050(.5)

x-.25x = 1050(.5)-1050(.25)

.75x = 1050/4=262.5

x= 262.5/.75= 262.5(4/3)=87.5(4)

x=350 mL of pure alcohol

1050-350

= 700 mL 25% alcohol

check the answers:

100-50=50

50-25=25

50/25=2=700/350

350(100%) + 700(25%) = 1050(50%)

350 + 700/4 = 1050/2

350 +175 = 525

525=525