Explain how abstraction is used in a gps system?

The average cost of one year at a private college in 2012-2013 is $43,289. the average grant aid received by a student at a private college in 2012-2013 is $15,680.   what is the average student contribution for one year at a private college in 2012-2013?

What engine component is shown in the above figure?

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)?