12.
[tex]we \: know \: that \\ \frac{sum \: of \: all \: quantities}{number \: of \: quantities} = mean \\ => \frac{26 + 22 + 32 + 28 + 35 + x}{6} = 30 \\ = > \frac{143 + x}{6} = 30 \\ = > 143 + x = 30 \times 6 \\ = > 143 + x = 180 \\ = > x = 180 - 143 \\ = > x = 37 \\ [/tex]
This is the answer.
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