math question

[yellowjellybean]

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Which of the following mixtures results in a 10-fold dilution
A. 9 PARTS SOLVENT WITH 1 PART SOLUTION
B 10 parts solvent with 1 part solution
C. 10% solvent with 90% solution
D. 91% solvent with 9% solution

I'm having a hard time understanding the math behind this. I think I understand why it is A. But the answer key says D is the same is B and I don't understand that.

Thanks

 

[QrtrLifeCrisis]

Which of the following mixtures results in a 10-fold dilution
A. 9 PARTS SOLVENT WITH 1 PART SOLUTION
B 10 parts solvent with 1 part solution
C. 10% solvent with 90% solution
D. 91% solvent with 9% solution

I'm having a hard time understanding the math behind this. I think I understand why it is A. But the answer key says D is the same is B and I don't understand that.

Thanks

B. Total Parts = 11; 10/11=91% solvent and 1/11=9% solute
D. Hence, same as B.