Homework

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I keep getting 0.66 I know it's not rite so I need help!

Show us the formula/steps and calculation you took to get your answer so we can see where you are going wrong

I keep getting 0.66 I know it's not rite so I need help!

1.5mg in a 30cc vial and what you need is 1mg in how many cc's right? So the equation looks like this:

1.5mg:30cc::1mg:?

Take away the wording and you get this:

1.5:30::1:x

Solve for X

I would look at it like this...you can divide down both 1.5 and 30 by 3. That would give you 0.5mg in 10cc. So what is X? 20cc

Moved to the general student discussion forum.

May be worth investing in a good book discussion medications and calculations

Definitely ask for additional help at school if you're having difficulty.

(Desired/Have)x Volume

Did you follow Edmeds explanation? I find the formula method much easier than ratio method, although I've never really tried to learn ratio method. (Desired/Have)x volume. The order (desired) is 1mg. The amount you have on hand (have) is 1.5 mg. Divide 1mg by 1.5mg and multiply by the volume, 30ml. ml and cc are the same thing. So your problem would look like this: 1mg/1.5mg x 30 ml = 20ml or 20cc's. Since the question is asking for cc's that's the way you need to write your answer.

It's a ratio problem. Edmed's explanation simplifies it into a structure that stays consistent across almost every calculation you'll ever do.

Remember how you set up ratio problems, then you cross multiply and divide to get your answer?

1 (want mg) x (wanted volume)

---------- = -----------------------

1.5 (have mg) 30mL (volume you have)

Traditionally, it would be 1*30, then divide that answer by the 1.5.

Because of the properties of multiplication and division, though, if the ratio is set up like this, with the x to the top right, you can just divide the left side, and multiply by whatever is on the bottom right. So, 0.66 * 30.

You were just forgetting to multiply your ratio of the mg of the drug against the volume of the solution the drug is in, to get the volume that you need. You solved that you needed 0.66 of the drug, but you forgot to solve that it meant you needed 0.66 of the solution.