The modulation frequency of an AM radio station is 250 KHz.

The question is incomplete and doesn't provide enough information to determine what the '10' refers to. The modulation frequency of 250 kHz only provides the frequency of the modulating signal in Amplitude Modulation (AM). To solve for something, we'd need a complete question, for example, asking for the carrier frequency given the sideband frequencies or the bandwidth. Without additional context, no solution can be provided.