Dave surveyed 80 7th-graders and 90 8th-graders. He found that about 75% of the 7th-grader like pop music, while 80% of the 8th-graders like pop music. Do more 7th-graders or more 8th-graders like pop music? Explain.

Step-by-step explanation:

There are 80 7th-graders and about 75% of them like pop music

This means that roughly 75% of the 80 7th-graders like pop music

so, 75 /100 X 80 like pop music

therefore, roughly 60 7th-graders like pop music

80 - 60 = 20

That means roughly 20 7th-graders don't like pop music

Also, there are 90 8th-graders and 80% of them like pop music

which means, 80 /100 X 90 like pop music

therefore, 72 8th-graders like pop music

90 - 72 = 18

This means 18 8th-graders don't like pop music

since 72 > 60

and    18 < 20

It is obvious that more 8th-graders like pop music