[tex] \frac{2 \times 1 + 3 \times 2 + 4 \times 3 + 5 \times 3 + 6 \times 7 + 7 \times 7 + 8 \times 4 + 9 \times 2 + 10}{1 + 2 + 3 + 3 + 7 + 7 + 4 + 2 + 1} = \\ \frac{2 + 6 + 12 + 15 + 42 + 49 + 32 + 18 + 10}{9 + 21} = \\ \frac{20 + 57 + 91 + 50 + 10}{30} = \\ \frac{77 + 151}{30} = \\ \frac{228}{30} = 7.6(media \: notelor)[/tex]
