A cookie recipe calls for 1 1/4 cups of flour and 1 1/2 cups of sugar. If the amount of the ingredients are increased proportionally and the amount of sugar was increased to 9 cups, how many cups of flour would be needed?

7.5 cups of flour would be needed

Step-by-step explanation:

Here, we shall be making a ratio comparison.

To do this, it is best we use decimal notations.

The ratio of cups of flour to cups of sugar in decimal notation would be;

1.25 to 1.5; This ratio is 1 to 1.2

Now, we have sugar increased to 9 cups; thus let the cup of flour be x

Using the ratio comparison;

1:1.2 = x:9

1/1.2 = x/9

1.2x = 9

x = 9/1.2

x = 7.5