Răspuns:
Explicație pas cu pas:
4.
Media clasei = (3 x 6 + 4 x 7 + 5 x 8 + 6 x 9 + 7 x 10) : (3 + 4 + 5 + 6 + 7)
= (18 + 28 + 40 + 54 + 70) : 25 = 210 : 25 = 8,4
5.
x = 2,7 = 27/10
y = 3/2
z = 1/x - 1/y = 10/27 - 2/3 = 10/27 - 18/27 = -8/27
z* (x - y^2) = -8/27 * (27/10 - 9/4) = -8/27 *(54/20 - 45/20) = -8/27 * 9/20
= -2/15
