At what height h above the ground does the projectile have a speed of 0.5v?

Express your answer in terms of v and the magnitude of the acceleration of gravity g.

If I'm not mistaken, there should have been an additional data for this problem. I have encountered a similar problem but it had these information,

K = 1/2mv^2

U = mgh

answer:

K = U

0.5mv ² = mgh

0.5v ² = gh

h = (0.5v ²) / g

Since the speed is 0.5 v:

h = [0.5 (0.5v) ² ]/g

h = (0.125v ²) / g

h = v ² / 8g