What is true regarding the cellular phone concept? a. a single radio broadcast tower system enables greater frequency reuse compared to a multiple cell phone system b. increasing base station transmit power is required to decrease the size of a cell c. by increasing the number and density of cells within a service area, you increase the overall complexity of the entire system d. decreasing the size of a cell expends greater power from the mobile device, and therefore reduces the device’s operating time

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)?