Mean is gotten as the sum of the terms divided by the number of terms. That is,
sum of the terms
40 +30 + 70 + 20 + 60 +10 +10 + 80 + 30 + 1010\;\frac{40\;+30\;+\;70\;+\;20\;+\;60\;+10\;+10\;+\;80\;+\;30\;+\;10}{10}1040+30+70+20+60+10+10+80+30+10
36010\;\frac{360}{10}10360 = \$36
