Question

Se stie ca media aritmetica a numerelor 21,39,48,a si b este 84,iar media aritmetica a numerelor 64 si 2a este 42. Determinati numarul b. Dau coroana

Answer 1

(21+39+48+a+b):5=84
84x5=420
21+39+48=108
a+b=420-108=312

(64+2a):3=42
64+2a=126
2a=126-64=62
a=62:2=31
a=31
b=312-31=281

Answer 2

Ma = (21+39+48+a+b):5=84
Ma = (108+a+b)=84*5
Ma = 108+a+b=420
a+b=420-108
a+b=312

(64+2a):3=42
64+2a=42*3
64+2a=126
2a=126-64
2a=62
a=62:2
a=31
b=312-31
b=281