Final answer:
To achieve the ordered dosage of 75 mcg, the patient should take half of a 0.15 mg tablet of Isoniazid, as the calculation shows that it requires 0.5 of a tablet to equal 75 mcg.
Step-by-step explanation:
The question refers to the calculation of the number of tablets needed to meet a specific dosage of a medication. In this case, we need to convert the ordered dose of Isoniazid from micrograms (mcg) to milligrams (mg) to match the available tablet strength.
To calculate the number of tablets, we convert the dosage ordered (75 mcg) to milligrams (mg) since 1 mg equals 1000 mcg. Thus, 75 mcg is equal to 0.075 mg. Now, since the available tablets are 0.15 mg each, we divide the ordered dosage in mg (0.075 mg) by the strength of each tablet (0.15 mg) to get the number of tablets:
Number of tablets = Ordered dosage (mg) / Tablet strength (mg)
Number of tablets = 0.075 mg / 0.15 mg
Number of tablets = 0.5
Therefore, the patient should take half of a 0.15 mg tablet to achieve the ordered dosage of 75 mcg.