8 gray buttons out of 20 buttons
A.2/5
B.4/10
C.2/3
D.5/2
40 boys out of 70students
A.3/7
B.1/2
C.4/7
D.7/10
A.2/5
B.4/10
C.2/3
D.5/2
40 boys out of 70students
A.3/7
B.1/2
C.4/7
D.7/10