NanaA wrote:

I'm sorry I am not comprehending this. Isn't it possible to still calculate an average using statement two as long as the numbers used have four more students in group 1? If you get the time, could you please elaborate on why statement two is insufficient? Thanks you !!

You can test statement 2 by pluggin in quick numbers

If class 1 has 5 students, then class 2 will have 1

The equation would be (5* 4.0 + 1 * 3.0) / ( 5 + 1) = 23 / 6 or 3 and 5/6

If class 1 has 6 students, then class 2 will have 2

The equation would be (6* 4.0 + 2 * 3.0) / ( 6 + 2) = 30 / 8 or 3 and 3/4

Since you get different answers, statement II is insufficient