From Einstein's equation of Photoelectric effect, we can write
For case 1: 21mv12=2hν0−hν0⇒21mv12=hv0 ... (i), where m is mass of electron, h is Planck's constant.
For case 2: 21mv22=5hν0−hν0⇒21mv22=4hν0 ... (ii)
From (1) and (2)
v2v1=41=21.
Hence, the ratio of v1 and v2 is 1:2.