In the sixth grade, math interest groups in three classes are 2 1 person. 1 the ratio of class to class 2 is 3: 4, and the ratio of class 2 to class 3 is 2: 1. Find the class number of 65,438+0.
2 1×3÷( 1+3/4+ 1/2)×3/4
=63÷9/4×3/4
=28×3/4
=2 1 person