Question 2.1 Spatial Index Structures (10 Points) Suppose we store a relation R(x,y) in a grid file. Both attributes have a range of values from 0 to 1000. The partitions of this grid file happen to be uniformly spaced: for x there are partitions every 20 units, at 20, 40, 60, and so on, for y the partitions are every 50 units, at 50, 100, 150, and so on a. How many buckets do we have to examine to answer the range query SELECT FROM R WHERE 310x AND x400 AND 520