Final answer:
To convert 4200 grams to pounds and ounces, divide by 453.6 to get 9.2597 pounds, then multiply the decimal part by 16 to get 4.1552 ounces, giving approximately 9 pounds and 4 ounces.
Step-by-step explanation:
To convert an infant's weight of 4200 grams to pounds and ounces, we use the equivalence: 1 lb = 0.4536 kg and 1 oz = 28.35 g. First, to convert grams to pounds, we divide the total grams by the number of grams in one pound (0.4536 kg * 1000 g/kg).
4200 g ÷ (0.4536 kg * 1000 g/kg) = 9.2597 pounds
Since there are 16 ounces in one pound, we take the decimal part (0.2597) and multiply it by 16 to get the ounces.
0.2597 pounds * 16 oz/pound = 4.1552 ounces
Therefore, a newborn infant weighing 4200 grams would be approximately 9 pounds and 4 ounces.