Final answer:
The safe dose for the child is 33.875 mg.
Step-by-step explanation:
To calculate the safe dose for the child, we need to find the child's body surface area (BSA) first. BSA can be calculated using the formula:
BSA = (height in cm * weight in kg)/3600
Substituting the given values:
BSA = (140 * 43.5)/3600 = 1.69375 m²
Now we can calculate the safe dose by multiplying the BSA by the recommended dose per square meter:
Safe dose = BSA * recommended dose = 1.69375 * 20 = 33.875 mg