Final answer:
To calculate a child's dose using Young's rule, multiply the adult dose by the ratio of the child's age to the child's age plus 12. For a 3-year-old child with an adult dose of 250 mg, the correct dose would be 50 mg.
Step-by-step explanation:
To compute a 3-year-old child's dose using Young's rule, we need to consider the age of the child in relation to the typical adult dose. Young's rule states that the child's dose is equivalent to the adult dose times the fraction of the child's age in years divided by the sum of the child's age plus 12. For a 3-year-old child and an adult dose of 250 mg, the calculation would be:
- Child's dose = (Child's age / (Child's age + 12)) × Adult dose
- Child's dose = (3 / (3 + 12)) × 250 mg
- Child's dose = (3 / 15) × 250 mg
- Child's dose = 0.2 × 250 mg
- Child's dose = 50 mg
Therefore, the appropriate dose for the 3-year-old child would be 50 mg.