Count the number of orders made from the store in city with population of 3000000 to 4000000.
number of order refers to OrderNumber; population of 3000000 to 4000000 refers to Population BETWEEN 3000000 AND 4000000
SELECT COUNT(T1.OrderNumber) FROM `Sales Orders` AS T1 INNER JOIN `Store Locations` AS T2 ON T2.StoreID = T1._StoreID WHERE T2.Population BETWEEN 3000000 AND 4000000