Assume an algorithm takes 5.6 seconds to execute on a single 1.9 GHz processor. 20% of the algorithm is sequential. Assume that there is zero latency and that the remaining code exhibits perfect parallelism. How long (in seconds) should the algorithm take to execute on a parallel machine made of 3 1.9 GHz processors?

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)?