Wednesday, 13 January 2016

CBSE UGC NET Computer Science Paper II Solved December 2015 - Part 4

31.       A data cube C, has n dimensions, and each dimension has exactly p distinct values in the base cuboid. Assume that there are no concept hierarchies associated with the dimensions. What is the maximum number of cells possible in the data cube, C?
(A) pn                  (B) p
(C) (2n-1)p+1     (D) (p+1)n
Answer: D
Explanation:
(a) What is the maximum number of cells possible in the base cuboid?
 pn.
This is the maximum number of distinct tuples that you can form with p distinct values per dimensions.
(b) What is the minimum number of cells possible in the base cuboid?
 p.
You need at least p tuples to contain p distinct values per dimension. In this case no tuple shares any value on any dimension.
(c) What is the minimum number of cells possible in the data cube, C?
(2n-1)×p+1.
The minimum number of cells is when each cuboid contains only p cells, except for the apex, which contains a single cell.
(d) What is the maximum number of cells possible (including both base cells and aggregate cells) in the data cube, C?
(p+1)n.
The argument is similar to that of part (a), but now we have p+1 because in addition to the p distinct values of each dimension we can also choose .
32.       Suppose that from given statistics, it is known that meningitis causes stiff neck 50% of the time, that the proportion of persons having meningitis is 1/50000, and that the proportion of people having stiff neck is 1/20. Then the percentage of people who had meningitis and complain about stiff neck is:
(A) 0.01%          (B) 0.02%
(C) 0.04%          (D) 0.05%
Answer: B
Explanation:
The computation is based on the simplified Bayes’ formula.
P{B|A} = (P{A|B}·P{B) / P{A}.
P{M|S} = probability that a person had meningitis, conditioned by the existence of stiff neck.
P{S|M} = probability that a person complains about stiff neck, conditioned by the existence of meningitis. = 50%=1/2
P{S} = proportion of people who complain about stiff neck. = 1/20
P{M} = proportion of people who had meningitis. = 1/50,000
Then:
P{M|S} = (P{S|M}·P{M}) / P{S} =(1/2 x 1/50,000) / 1/20 = 0.0002 = 0.02%
33.       ................. system is market oriented and is used for data analysis by knowledge workers including Managers, Executives and Analysts.
(A) OLTP                       (B) OLAP
(C) Data System          (D) Market System
Answer: B
34.       .................. allows selection of the relevant information necessary for the data warehouse.
(A) The Top-Down View         (B) Data Warehouse View
(C) Data source View             (D) Business Query View
Answer: A
35.       The hash function used in double hashing is of the form:
(A) h(k, i)=(h1(k)+h2(k)+i)mod m                    (B) h(k, i)=(h1(k)+h2(k)-i)mod m
(C) h(k, i)=(h1(k)+ih2(k))mod m                      (D) h(k, i)=(h1(k)-ih2(k))mod m
Answer: C

36.       In the following graph, discovery time stamps and finishing time stamps of Depth First Search (DFS) are shown as x/y where x is discovery time stamp and y is finishing time stamp.
It shows which of the following depth first forest?
(A) {a,b,e} {c,d,f,g,h}                (B) {a,b,e} {c,d,h} {f,g}
(C) {a,b,e} {f,g} {c,d} {h}           (D) {a,b,c,d} {e,f,g} {h}
Answer: A
37.       The number of disk pages access in B-tree search, where h is height, n is the number of keys, and t is the minimum degree, is:
(A) θ(logn h*t)                (B) θ(logt n*h)
(C) θ(logh n)                  (D) θ(logt n)
Answer: D
38.       The inorder traversal of the following tree is:
(A) 2 3 4 6 7 13 15 17 18 18 20
(B) 20 18 18 17 15 13 7 6 4 3 2
(C) 15 13 20 4 7 17 18 2 3 6 18
(D) 2 4 3 13 7 6 15 17 20 18 18
Answer: D
39.       An ideal sort is an in-place-sort whose additional space requirement is ...............
(A) O(log2n)                  (B) O(nlog2n)
(C) O(1)                         (D) O(n)
Answer: C
40.    Which of the following is not a congestion policy at network layer?
(A) Flow Control Policy
(B) Packet Discard Policy
(C) Packet Lifetime Management Policy
(D) Routing Algorithm
Answer: A


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