If radius of cylinder and sphere r same and vol of sphere and cylinder r same what is d ratio between the radius and height of the cylinder i. R= H ii. R= (3/4)H iii. R = (4/3)H iv. R=2/3H?

If the volumes are the same, we have
  4/3*π*r^3 = π*r^2*h
  4/3*r = h    (divide by π*r^2)
  r = 3/4*h    (multiply by 3/4)
The second (ii) answer matches this.