2.
b)
[tex]x_{w} = \frac{x_1\cdot w_1 + x_2\cdot w_2 + x_3\cdot w_3 + ...+ x_{n}\cdot w_{n}}{w_1 + w_2 + w_3 + ... + w_{n}}\\\\x_{w} = \frac{3\cdot3 + 6\cdot 5+10\cdot2+8\cdot7}{3+5+2+7} = \frac{9 + 30+20+56}{3+5+2+7} = \frac{115}{17}\approx6,76[/tex]
