Question

Calculati media aritmetica ponderata a numerelor : 12,5 ; 7 intregi si 5/12 si 3/4 ,care au respectiv ponderile x^2,x+4 si 4x^2+4, suma ponderilor fiind 30

Answer 1

 x^2 +x+4+4x^2 +4=30

5x^2 +x-22=0

(x-2)(5x+11)=0

x=pondere, rezulta x>0

x-2=0, x=2

Deci ponderile sunt: 4, 6 si 20.

[(4*12,5)+6*(7 si 5/12)+20*(3/4)]/30=

=(50+6*89/12 +15)/30=

=(50+89/2 +15)/30=

=(65+89/2)/30=219/(2x30)=73/20=3,65