Calculate the total beat of the crimes reported in a community area in the central side with population of 50,000 and above.
the central side refers to side = 'Central'; population of 50,000 and above refers to population > '50000'; total beat = sum(beat) where side = 'Central' and population > '50000'
SELECT 1.0 * SUM(CASE WHEN T1.population > 50000 THEN T2.beat ELSE 0 END) AS sum FROM Community_Area AS T1 INNER JOIN Crime AS T2 ON T2.community_area_no = T1.community_area_no WHERE T1.side = 'Central'