Final answer:
The recommended dosage of acetaminophen for a child who weighs 75 pounds is 480 mg by using direct variation and setting up a proportion based on the dosage given to a 25-pound child.
Step-by-step explanation:
The question is about calculating the correct dosage of acetaminophen for a child based on their weight, which is an example of a direct variation problem. Direct variation is indicated by phrases such as 'the dosage usually varies directly as the weight of the child.'
To find the correct dosage for a 75-pound child, we use the fact that a 25-pound baby receives 160 mg. We set up a proportion since the dosage varies directly with weight: 160 mg / 25 pounds = x mg / 75 pounds, where x represents the desired dosage for the 75-pound child.
Solving for x, we get: x = (160 mg / 25 pounds) * 75 pounds = 480 mg. Therefore, the recommended dosage of acetaminophen for a child who weighs 75 pounds is 480 mg.