# pharmacy math questions

by Magda
(Frisco, tx)

Drug M is available in 1g vials, with instructions to add 15.6 mL of sterile water to obtain a total volume of 16 mL. How many mL will be required for a 875mg dose if the dose is added to 50 mL of D5W.
A. 1.1 mL
B. 0.8 mL
C. 14 mL
D. 16 mL

### Comments for pharmacy math questions

 mixture math by: Anonymous You could basically do this one in your head through process of elimination. Obviously 16 is too many because it would be all 1000MG, the others are way too low. So, easy to guess 14.Or, do a cross multiplication equation.1000 - - 875 ------ = ------16mL - - -X X = 1414mL is what is needed.

 simple way by: Johnson Meloottu Every 1000mg, we can make 16ml.That means every 62.5 mg, we can make 1ml.(16/1000= 62.5mg)Here we have 875 mg. So we can make 14 ml (875/62.5)

 How by: Anonymous That can't be right.. It asked how many mL's would it require to get a dose of 875mg IF the drug was added to 50 mL of D5W.. It's been diluted therefore it should require more amount to reach a dose of 875mg since only 16mL gave a dose of 1000mg…Unless I'm totally reading this wrong...This is the part that's tricking you:"How many mL will be required for a 875mg dose if the dose is added to 50 mL of D5W."It's asking about it before it's diluted.This question is poorly written. However, you might see stuff like this on the PTCB. So, you have to use your left brain some, and decipher these.

 Need clarification by: Lexie I do not understand how you get the 1000 mg. Please explain - thanks!

 you get the 1000 mg by: Anonymous You get the 1000mg because 1g = 1000 mg