Final answer:
The cost of 49 avocados, when 7 avocados cost 5 dollars, is calculated by finding the unit price and then multiplying by the desired quantity, resulting in a total cost of $35.
Step-by-step explanation:
If 7 avocados cost 5 dollars, then to find the cost of 49 avocados, we can set up a proportion based on the principle that the cost is directly proportional to the number of avocados. This concept is similar to calculating costs in examples where 10 apples cost 5 dollars, or 12 bananas cost 2 dollars and 40 cents.
To solve this, first we find the cost of one avocado, which is 5 dollars ÷ 7 avocados = $0.714 (approximately). Then, we multiply the cost of one avocado by the number of avocados we want to purchase (49 avocados), resulting in 0.714 × 49 = $35. So, 49 avocados will cost $35.