Question 12

One-third of a milliliter is needed to provide 150,000 units.

To determine the volume needed to provide 150,000 units from a solution that contains 450,000 units per milliliter, one can set up a simple ratio. Since 150,000 units is one-third of 450,000 units, the required volume is one-third of one milliliter.

A) 1/3

This option is correct because if 450,000 units are present in 1 milliliter, then to find out how many milliliters are needed for 150,000 units, the calculation is 150,000 units divided by 450,000 units per milliliter, which simplifies to 1/3 milliliters.

B) 4/3

This option is incorrect because 4/3 milliliters would provide 600,000 units of the antibiotic (since 450,000 units/mL x 4/3 mL = 600,000 units), which exceeds the required 150,000 units.

C) 1/4

This option is also incorrect. Calculating 1/4 milliliters would yield only 112,500 units (450,000 units/mL x 1/4 mL = 112,500 units), which is less than the required 150,000 units.

D) 3

This option is incorrect as well, as 3 milliliters would provide 1,350,000 units (450,000 units/mL x 3 mL = 1,350,000 units), greatly exceeding the 150,000 units needed.

Conclusion

The calculation confirms that 1/3 milliliters is the accurate volume needed to achieve 150,000 units from a solution of 450,000 units per milliliter. All other options either provide too much or too little of the required dosage, making them incorrect. Therefore, option A is definitively the right answer.