Final answer:
The relationship between the cost and the number of pizzas at Papa's Slice of Italy pizzeria is not proportional because the cost per pizza decreases as the number of pizzas purchased increases, indicating a volume discount.
Step-by-step explanation:
To determine whether the relationship between the cost and the number of pizzas is proportional, we need to calculate if there is a consistent unit rate. A proportional relationship means that the ratio between the cost and the number of pizzas should be the same for every quantity. Let's calculate the cost per pizza for each of the given quantities:
- For 1 pizza: $12.50 / 1 pizza = $12.50 per pizza
- For 2 pizzas: $20 / 2 pizzas = $10.00 per pizza
- For 3 pizzas: $27.50 / 3 pizzas = $9.17 per pizza
- For 4 pizzas: $35 / 4 pizzas = $8.75 per pizza
Since the cost per pizza is not consistent, the relationship is not proportional. We can see that the more pizzas you buy, the less the cost per pizza becomes, which indicates that there is a volume discount. Therefore, we cannot find a unit rate applicable for every quantity since the pricing structure differs depending on the number of pizzas bought.