a Dr orders 500mg of tylenol. you have tylenol in a vial that contains 350 mg for every .5 teaspoons. How many mL will you give?

Question

I cannot remember how to set this problem up or how to solve it.  Any help would be appreciated. 

Answer 1

First you have to figure out how many teaspoons to give.  If you're working on ratios and proportions, then you would set it up this way:

 

350 is to .5 as 500 is to x, or 350 / .5 = 500 / x

 

This is solved by "cross multiplying": 

350 x = .5 * 500

x = .5 * 500 / 350 = .714 teasppons.

 

Now you have to convert teaspoons to mL.  1 tsp is 4.929 mL  So again you can do it as a ratio:

 

1 is to 4.929 as .714 is to x

 

That gives you:

 

x = 4.929 * .714 = 3.519 mL