In a year, on average, how many personswere killed in industrial accidents and coal mines together ?

Average persons were killed in industrial accidents = $$ \frac{1200 + 900 +1100 + 800}{4} $$

                                                                             = $$ \frac{4000}{4} = 1000 $$

Average persons were killed in coal mines = $$ \frac{300 + 150 + 200 + 200}{4} $$

                                                               = $$ \frac{850}{4} = 212.5 $$

Total = 1000 + 212.5 = 1212.5