Use conservation of energy.
KEi +PEi = KEf +PEf
Since it is rolling KE must be split into translational and rotational components.
KEr = 1/2 Iω2. (ω = v/r) KEr = 1/2 (1/2 MR2)(v/R)2 = 1/4Mv2
KEt = 1/2 mv2
(1/4Mvi2 + 1/2Mvi2) + (mghi) = (1/4Mvf2 + 1/2Mvf2) + (mghf)
Since mass is in every term it can be cancelled out.
The final height (hf) is zero because it is at the bottom of the ramp.
The initial height (hi) is 1.2 m as stated in the problem.
The initial velcity (vi) is 0 because it starts from rest.
Therefore, ghi = 3/4vf2
9.8(1.2) = 3/4v
f2
vf2 = 15.68
vf = 3.96 m/s