To determine if the quantities in the data table are in a proportional relationship, we need to check if the ratios of the quantities and their corresponding costs are constant.
The ratio of 2 pounds of bananas to its cost is 2.50/2 = 1.25.
The ratio of 3 pounds of bananas to its cost is 3.75/3 = 1.25.
The ratio of 5 pounds of bananas to its cost is 6.25/5 = 1.25.
The ratio of 7 pounds of bananas to its cost is 8.75/7 = 1.25.
Since the ratio of the quantities and their corresponding costs is constant (1.25), the quantities in the data table are in a proportional relationship.
Therefore, the answer is 1.