What would you expect to happen to the number of high tides in any given area if the rate of Earth's rotation doubles?

high tides would also double within the span of 24 hours.

Explanation:

If the Earth's rotation doubled then the number of high tides would also double within the span of 24 hours. This is because low and high tides depend on the Earth's pull toward's the Moon, since as the ocean bulges toward the moon, a high tide is created. Therefore if Earth's rotation doubled, this would mean that pull towards the Moon would happen twice in 24 hours, and thus causing high tide twice.