Ratio Calculations HELP

PTgirl3 wrote the following at 15:38 on 11/30/10;

How many grams of Potassium permanganate should be used in preparing 300mL of a 1/2:1250?

I don't know how do this problem...am I suppose to multiply or divide? And what do I multiply/divide? Please help me! Thank you so much in advance!

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moderator wrote the following reply at 10:00 on 12/4/10;

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Answer to potassium permanganate problem

moderator wrote the following reply at 10:06 on 12/4/10;

This is a very poorly written problem. Was the person who wrote it a pharmacist? Instead of writing 1/2:1250, your instructor should've written 0.5:1250 or better yet, 1:2500. It is not a division problem but a ratio problem. There is half a gram of K permanganate (K pm)in 1250 mL of solution. If you make 300 mL instead, how much K pm do you need?

0.5g/1250mL = X/300mL
(0.5x300)/1250 = X
X = 0.12g K pm

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