At a school 40% of the sixth graders students said that hip hop is their favorite kind of music. If 100 sixth graders students prefer hip hop music, how many sixth graders are at the school?

If 100 students make up 40% of the 6th grade population, then 50 students make up 20% of the 6th grade population. 20% * 5 makes 100% so if your multiply 50 by 5 you'd get your population.

50 * 5 = 250 sixth-graders

60 percent i'm sure