In a random survey of 250 students. 70 are in the band. Total population is 1500. How many are in the band

Total population of what? The town? The school?

Also, realistically, the sample rational is too small.
In sampling, where was sampling done, was it in the hallway to the band?

Was it after school, when mostly music or sports programs were going?

I know what you are wanting, but again, this sampling would have too high a error factor to follow to any conclusions.
** not that your teacher would like that answer, but that is really the real answer.