UGC NET Computer Science June 2014 Solved Paper II - Part 4

31.       In a paged memory management algorithm, the hit ratio is 70%. If it takes 30 nanoseconds to search Translation Look-aside Buffer (TLB) and 100 nanoseconds (ns) to access memory, the effective memory access time is
(A) 91 ns           (B) 69 ns
(C) 200 ns         (D) 160 ns
Answer: D
The percentage of times that a page number is found in the associative registers is called the hit ratio. A 70% hit ratio means that we find the desired page number in the associative registers 70% of the time. If it takes 30 nanoseconds to search the associative registers, and 100 nanoseconds to access memory, then a mapped memory access takes 130 nanoseconds when the page number is in the associative registers. If we fail to find the page number in the associative registers (30 nanoseconds), then we must first access memory for the page table and frame number (100 nanoseconds), and then access the desired byte in memory (100 nanoseconds), for a total of 230 nanoseconds.
Effective access time = 0.70 x 130 + .30 x 230 = 91 + 69= 160
32.       Match the following:
List-I                                                               List-II
a. Multilevel feedback queue                        i. Time-slicing
b. FCFS                                                 ii. Criteria to move processes between queues
c. Shortest process next                     iii. Batch processing
d. Round Robin Scheduling             iv. Exponential Smoothening
      a    b    c    d
(A) i     iii    ii    iv
(B) iv   iii    ii    i
(C) iii   i     iv    i
(D) ii    iii   iv    i
Answer: D
33.       Consider a system with five processes P0 through P4 and three resource types R1, R2 and R3. Resource type R1 has 10 instances, R2 has 5 instances and R3 has 7 instances. Suppose that at time T0, the following snapshot of the system has been taken :
Assume that now the process P1 requests one additional instance of type R1 and two instances of resource type R3. The state resulting after this allocation will be
(A) Ready State           (B) Safe State
(C) Blocked State        (D) Unsafe State
Answer: B
34.       Match the following:
List-I                                                      List-II
a. Contiguous Allocation       i. This scheme supports very large file sizes.
b. Linked allocation                 ii. This allocation technique supports only sequential files.
c. Indexed allocation               iii. Number of disks required to access file is minimal.
d. Multi-level indexed                         iv. This technique suffers from maximum wastage of space in storing pointers
      a    b    c    d
(A) iii    iv   ii     i
(B) iii    ii    iv    i
(C) i     ii    iv   iii
(D) i    iv    ii    iii
Answer: B
35.       Which of the following out commands will output "onetwothree"?
(A) for val; do echo-n $val; done < one two three
(B) for one two three; do echo-n-; done
(C) for n in one two three; do echo-n $n; done
(D) for n in one two three {echo-n $n}
Answer: C

36.       Merge sort makes two recursive calls. Which statement is true after these two recursive calls finish, but before the merge step?
(A) The array elements from a heap
(B) Elements in each half of the array are sorted amongst themselves.
(C) Elements in the first half of the array are less than or equal to elements in second half of the array
(D) All of the above
Answer: B
37.       A text is made up of the characters α, β, γ, δ and σ with the probability 0.12, 0.40, 0.15, 0.08 and 0.25 respectively. The optimal coding technique will have the average length of
(A) 1.7                (B) 2.15
(C) 3.4                (D) 3.8
Answer: B
38.       Searching for an element in the hash table requires O(1) time for the ............... time, whereas for direct addressing it holds for the ............. time.
(A) worst-case, average          (B) worst-case, worst-case
(C) average, worst-case         (D) best, average
Answer: C
39.       An algorithm is made up of 2 modules M1 and M2. If time complexity of  modules M1 and M2 are h(n) and g(n) respectively, the time complexity of the algorithm is
(A) min (h(n),g(n))
(B) max (h(n),g(n))
(C) h(n) + g(n)
(D) h(n) * g(n)
Answer: B
40.    What is the maximum number of parenthesis that will appear on the stack at any one time for parenthesis expression given by
( ()     (())         (()) )
(A) 2       (B) 3
(C) 4       (D) 5
Answer: B

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