mixing solutions problem

by April
(MI, USA)

How much 75% ethanol is needed to make 300ml of 30% ethanol?
A. 80mL
B. 120mL
C. 180mL
D. 240mL

Would really appreciate it if someone could help me out by writing out the problem (show how to solve). Thank you

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mixing solutions problem

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Jan 18, 2012
alcohol
by: Anonymous

want
-----X qty= solution
have

30%
---- X 300 ml= 120 ml
75%

Jan 10, 2012
simple
by: Riduan

You can do both ways; 75%- - - 30
30%
0%- - - 45

Now, the next step:30/75.300=120 ml

or

(C1)(V1) = (C2) (V2)
(.30)(300) = (.75) (X)
90 /.75 = 120 ml

Oct 27, 2011
Pharmacy Math Solutions
by: Anonymous

Calculate how much mixture or solution must be given so that the patient receives the correct dose of active ingredient.

Requires 50mg of active ingredient using a 5% w/w mixture

Jul 27, 2011
there is a short cut
by: Anonymous

Times the two that are close together and divide by the one that is far away!

Jun 29, 2011
mixing solutions problem
by: Anonymous

How much 75% ethanol is needed to make 300ml of 30% ethanol?
A. 80mL
B. 120mL
C. 180mL
D. 240mL

C1 x V1 = C2 x V2

30% x 300mL = 75% x
9000 = 75x
9000/75 = x
120mL = x

answer B.

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