ATI TEAS (Test of Essential Academic Skills) Version 7MathematicsEasy
A patient's medication is available in a concentration of 250 mg per 5 mL. If the physician orders a dose of 375 mg, how many milliliters (mL) should the nurse administer?
- A7.5 mL
- B5 mL
- C12.5 mL
- D10 mL
Show answer & explanationAnswer & explanation
Correct answer: A. 7.5 mL
Use a proportion to solve: (250 mg / 5 mL) = (375 mg / x mL). Cross-multiply: 250x = 5 * 375. 250x = 1875. x = 1875 / 250 = 7.5 mL.
Why the other options are wrong
- B. This is the volume for 250 mg, not 375 mg.
- C. Incorrect; significantly overestimates the required volume.
- D. Incorrect; this would be the volume for 500 mg.
Dosage Calculation by Proportion
Using proportional relationships to determine the correct volume of medication based on desired dose and available concentration.
- Set up a ratio of 'what you have' to 'what you want'.
- Ensure units are consistent on both sides of the proportion.
- Cross-multiplication is a common method to solve.
Memory trick: Have over mL, Equals Want over X, then Cross-Multiply!