How many pages will be read from disk to answer each of the following queries. Assume that the buffer pool is empty before each query executes, and that it is large enough to hold the entire database. Assume also that 4 tuples from the base relation fit on one page in the data file and that all pages are full: Look up all tuples with search key value of 40 if the index is clustered. Look up all tuples with search key value of 40 if the index is unclustered. Look up all tuples with search key value in the range [60, 90] if the index is clustered. Look up all tuples with search key value in the range [60, 90] if the index is unclustered. Assume the worst-case scenario in terms of how the keys are stored in pages.

1. (15 points ) Consider the following B+ tree index