Question

Determinati numarul rational x stiimd ca media aritmetica ponderaa a numerelor 2,4,6 si x,cu ponderile 9,7,5 si respectiv 3, este egal cu 4,1(6)?? 

Answer 1

(2*9+4*7+6*5+x*3)/(9+7+5+3)=4,1(6)
(18+28+30+x*3)/24=25/6
(76+x*3)/24=25/6
6(76+3*x)=24*25
76+3*x=4*25
76+3*x=100
3*x=100-76
3*x=24
x=24:3
x=8