Question

You will need _____ml of the 95% solution

Answer 1

70 mL=25% alcohol

?mL=90% alcohol

90×70÷25

=252 mL

I think do like this....I'm not sure

Hope this help you

Answer 2

9514 1404 393

Answer:

  420 mL

Step-by-step explanation:

Let x represent the amount of the 95% solution needed in the mixture. The the total amount of alcohol in the mixture is ...

  0.25×70 + 0.95(x) = 0.85(70 +x)

  0.10x = 42 . . . . . . . . subtract 17.5+0.85x

  x = 420 . . . . . . . . divide by 0.10

You will need 420 mL of the 95% solution.

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Additional comment

There will be 70+420 = 490 mL of solution, of which 85%, or 0.85×490 = 416.5 ml is alcohol. That alcohol is the total of 0.25×70 = 17.5 mL of alcohol from the 25% solution and 0.95×420 = 399 mL of alcohol from the added 95% solution. (17.5 +399 = 416.5)