Răspuns :
g- nr bile galbene
r- nr bile rosii
g+r=12 g=1/3*12=12/3=4
r=12-g=12-4=8
fractii: g: 4/12=1/3
r: 8/12=2/3
r- nr bile rosii
g+r=12 g=1/3*12=12/3=4
r=12-g=12-4=8
fractii: g: 4/12=1/3
r: 8/12=2/3
g- nr bile galbene
r- nr bile rosii
g+r=12 g=1/3*12=12/3=4
r=12-g=12-4=8
fractii: g: 4/12=1/3
r: 8/12=2/3
r- nr bile rosii
g+r=12 g=1/3*12=12/3=4
r=12-g=12-4=8
fractii: g: 4/12=1/3
r: 8/12=2/3