For this problem we have the following table given:
Grapes Blueberries
2 0.5
6 1.5
20 5
24 6
As we can see for any row that we select we satisfy the following proportion:
![(2grapes)/(0.5blue)=4,(6grapes)/(1.5blue)=4](https://img.qammunity.org/2023/formulas/mathematics/college/5uj4p7drhkfqga8mkl2p71eyu1rx729ple.png)
![(20grapes)/(5blue)=4,(24grapes)/(6blue)=4](https://img.qammunity.org/2023/formulas/mathematics/college/101cs5nhxf0ko6csgoniynt8swmhlzlv7c.png)
So we can conclude that the ratio of Grapes: Blueberries is 4. In order to solve the question we know that Mandie is making 15 cups of fruit salad and we want to know the ratio of grapes to blueberries. And the best answer would be:
12:3
![(12grapes)/(3blueberries)=4](https://img.qammunity.org/2023/formulas/mathematics/college/vvzclxvsqs2f4bmj6mcxpw7npusco9gyiq.png)