When the light of frequency `2 v_(0)` (where `v_(0)` is threshold frequency), is incident on a metal plate, the maximum velocity of electrons emitted is `v_(1)`. When the frequency of the incident radiation is increased to `5 v_(0)`, the maximum velocity of electrons emitted from the same plate is `v_(2)`. the ratio of `v_(1)` to `v_(2)` is