Data Sufficiency

What is the ratio of the number of cups of flower to the number of sugar required in a certain cake recipe?

(1) the number of cups of flower required in the recipe is 250 percent of the number of cups of sugar required in the recipe

(2) 1,5 more cups of flower than cups of sugar are required in the recipe

Why the #2 is insufficient? please explanations

Question
The question is asking for the ratio of flower to sugar (let's call Flower, F, and Sugar, S). So we need to find
F/S = ???

You seem to understand that I. is sufficient first, but let's see it:

I. Cups of flower is 250% of cups of sugar.
therefore ->
F = 2.5S
->
F/S = 2.5
We have the ratio and this is sufficient.

II. 1.5 more cups of flower than sugar.
This means:
F = S + 1.5 or F - S = 1.5

But you cannot separate F and S out to make a ratio (F/S). If you divided both sides by S, just to try, you would get:

F/S = (S+1.5)/S

which still means you don't have real numbers for your ratio.

therefore, we know that I. is sufficient and II is not, the answer is (A)

yes, the answer is A