Hello Terry Christie,
That is different for each individual. You need to keep in mind if the person is cleared for a low, medium or high intensity level. Then their age, heartrate, and range of motion with limb length come into play. Therefore, there is not a numerical answer for this question.
With no potential problems to consider, the music tempo for a group class, as stated in the ACE Group Fitness Instructor Manual suggests:
100-130 tempo or B.P.M. You will want to decide if the music is in the foreground or background, also.