If the highest frequency modulating a carrier is 5 kHz, then the number of AM broadcast stations accommodated in a 90 kHz bandwidth are ______

In amplitude modulation (AM), the bandwidth required for each broadcast station is twice the highest modulating frequency.

Given that the highest modulating frequency is 5 kHz, the bandwidth per station is $$2 \times 5 = 10$$ kHz.

The total available bandwidth is 90 kHz. Therefore, the number of AM broadcast stations that can be accommodated is $$\frac{90}{10} = 9$$.