Applying Einstein's Photoelectric Equation,
K.E = E − Wo
K.E = hν − hνo
In first case, K.E1 = h(3.2×1016 − νo)
In second case, K.E2 = h(2.0×1016 − νo)
It is given in that (K.E1) = 2(K.E2)
Hence, [h(3.2×1016 − νo)] = 2[h(2.0×1016 − νo)]
On solving,
νo = 8 × 1015 Hz