1.
(a+b+c)/3=27,48 =>a+b+c=82,44
a=18,72 =>b+c=82,44-18,72 =>b+c=63,72
Media aritmetica (b+c)/2=31,86
2.
(a+b+c+d)/4=43,56 =>a+b+c+d=174,24
(e+f+g+h+i)/5=36,27 =>e+f+g+h+i=181,35
(a+b+c+d+e+f+g+h+i)/9=?
(174,24+181,35)/9=39,51
3.
a
a+1
a+2
a+3
a+4
a+5
a+6
(a+a+1+a+2+a+3+a+4+a+5+a+6)/7=84
7a+21=588
7a=588-21
7a=567 =>a=81
Numerele sunt 81, 82, 83, 84, 85, 86, 87.