Question 1071082
Do it like this one:
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A pharmacist has 4 quarts of a 15% solution of iodine. How much alcohol must be added to reduce it to a 10%solution of iodine?
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 Assuming alcohol is a solvent for iodine,
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 Add Q quarts
 4*15 + Q*0 = (4+Q)*10
 Q = 2