How do you dilute 91 percent alcohol to 0.05 percent alcohol?

Answer 1

alcohol percentages are usually volume percentages. .05% means 0.0005

(0.91 x)/(x+y) = 0.0005

0.91 x = 0.0005 x + 0.0005 y

0.9095 x = 0.0005 y

y = 1819 x

so for every 1 ml of the 91% solution add 1819 ml of water.