Question

If the dosage for a medication is 225mg/lb, how many grams should a 25-lb child be given?

Answer 1

Answer:

5.625 grams

Explanation:

Start your equation with what you have been given.  Place the units you need in your answer on the right side of the equal sign.

225mg

-----------   X  -----------   X ------------- =   ?   g

   lb

Now start to fill in your equation and use a conversions to get rid of the units you don't want.  Convert mg into grams first.  The child's weight (25 lb) is placed over 1 just to get the equation lined up properly so you can see how the units cancel out.

225 mg                 1 g                  25 lb            5.625 g

---------------   X   ---------------  X   -------------  =   ---------------

   lb                    1000 mg                 1                  1

The lb on the top and bottom cancel each other out and you are left with just grams.  Even though it is over one, that is the same at just 5.625 grams.