Line Plots · Hard problem

A line plot shows how much juice, in cups, is in each of several glasses. Above $\dfrac{1}{4}$ there are $4$ X's, above $\dfrac{1}{2}$ there are $3$ X's, and above $\dfrac{3}{4}$ there are $4$ X's. Some more glasses, each holding $\dfrac{1}{2}$ cup, are added so that there are exactly $7$ cups of juice in all. How many X's are above $\dfrac{1}{2}$ now?