Answer:
You need to know the weight in lb of 1 apple (or how manly apples there are in a 1 lb bag of apples)
Step-by-step explanation:
Option a) presents the price for unit of apple: 10 apples for $10.50. So, the price of 1 apple is calculated as $10.50/10 = $1.05
Option b) presents the price for weight of a bag of apples: 3 lb bag of apples for $5.00. So, the price for 1 lb bag of apples is $5.00/3 = $1.66/lb. But we don't know how many apples there are in a 1 lb bag.
If we knew the approximate weight in lb of an apple, we would know how many apples there are in a 1 lb bag and then we can compare with the price for unit (option b vs option a). For example, if there is 1 apple in a 1 lb bag, option b) is more expensive than option a) ⇒ $1.66/apple > $1.05/apple