calculation

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Husseinmr

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Aerosol OT (AOT) is used in veterinary medicine as a laxative. If 250 g of AOT is dissolved in 1 000 mL of glycerin (density of glycerin is 1.25 g/mL), the concentration of AOT in the solution is:
a. 12.5% w/w.
b. 16.7% w/w.
c. 20.0% w/w.
d. 23.8% w/w.
e. 25.0% w/w.

in PEBC the right answer is b ,i solve it :
mass of glycerine 1.25x1000=1250g
250/1250=x/100
x=20%
please any one explain me where is my mistake?
 
%W/W = Weight of AOT / (Weight of AOT + Weight of Glycerin)

You forgot to add up the weight of AOT and Glycerin in the denominator.

Hope that helps.
 
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