media aritmetică=2•4+3•5+3•6+4•7+5•8+6•9+2•10/25
=8+15+18+28+40+54+20/25=183/25=7,32
media ponderată=2•4+3•5+3•6+4•7+5•8+6•9+2•10/2+3+3+4+5+6+2=
=183/2+6+4+11+2=183/8+15+2=183/23+2=183/25=7,32
media ponderată=p1•x1+p2•x2+...+pn•xn/p1+p2+...+pn
x1, x2, x3, xn--->nota
p1, p2, p3, pn--->numărul elevilor care au obținut nota
media aritmetică:(a+b) /2
(a+b+c) /3
