Final answer:
For an 18-month-old weighing 23 pounds,the amount of ibuprofen to be administered would be 52.15 mg.
Step-by-step explanation:
The usual dose of ibuprofen is 5 mg per kilogram of body weight when the fever is under 102.5°F. In this case, the 18-month-old weighs 23 pounds, which is approximately 10.43 kilograms. Therefore, the amount of ibuprofen to be administered would be:
10.43 kilograms × 5 mg/kg = 52.15 mg
Therefore, the correct option would be 52 mg. None of the given options align exactly with this answer, so it seems like there might be a mistake in the options provided.