There are 70 students in the school band. 40% of them are sixth graders, 20% are seventh graders, and the rest are eighth graders.

How many sixth graders, how many seventh graders and how many eighth graders?

Sixth graders: 14

Seventh graders: 28

Eighth graders: 28

Step-by-step explanation:

To solve this you just have to use a rule of three to solve the percentages, remember that the 100% will be the 70 students, and we solve each case separetly:

70 students = 100%

sixth grades = 40%

Sixth grades = (40*70) / 100

Sixth graders = 28

70 students = 100%

seventh grades = 20%

seventh graders = (20*70) / 100

Seventh graders=14

So if we have that the rest of the students are eighth graders, we just add up the sixth and seventh graders and withdraw them from the total:

28+14=42

70-42=28

SOwe have that the eighth graders are 28