Rob just got a new idea for the movie he's making, and he wants to put in late hours to get it done. which of the following statements shows how rob's friends could be a positive influence? "why don't you quit making movies if they force you to stay up so late each night? " "if you work through the night for two days in a row, you can get the whole thing done." "we should get some pizzas and stay up the entire weekend working on it together." "why don't you work a little bit each day instead so you don't end up losing sleep? "

Suppose there is a relation r(a, b, c) with a b+-tree index with search keys (a, b).1. what is the worst-case cost of finding records satisfying 10 < a < 50 using this index, in terms of the number of records n1, retrieved and the height h of the tree? 2. what is the worst-case cost of finding records satisfying 10 < a < 50 and 5 < b < 10 using this index, in terms of the number of records n2 that satisfy this selection, as well as n1 and h defined above? 3. under what conditions on n1 and n2, would the index be an efficient way of finding records satisfying the condition from part (2)?