ISRO CS 2018

Question 1

The difference between a named pipe and a regular file in Unix is that

• A. Unlike a regular file, named pipe is a special file
• B. The data in a pipe is transient, unlike the content of a regular file
• C. Pipes forbid random accessing, while regular files do allow this.
• D. All of the above

Answer: (C)

ISRO CS 2018 UNIX
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Question 2

A class of 30 students occupy a classroom containing 5 rows of seats, with 8 seats in each row. If the students seat themselves at random, the probability that the sixth seat in the fifth row will be empty is

• A. 1/5
• B. 1/3
• C. 1/4
• D. 2/5

Answer: (C)

ISRO CS 2018 Probability
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There are 5 rows with 8 seats in each row. So, there are total 40 seats If sixth seat in the fifth row is empty then 30 students have 39 choices of seats So, ways to choose from given choices = ³⁹C₃₀ But, total ways to choose = ⁴⁰C₃₀ Probability = ³⁹C₃₀ / ⁴⁰C₃₀ Probability = 1/4 Option (C) is correct.

Question 3

The domain of the function log( log sin(x) ) is

• A. 0 < x < π
• B. 2nπ < x < (2n + 1) π , for n in N
• C. Empty set
• D. None of the above

Answer: (C)

ISRO CS 2018 Numerical Methods and Calculus
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log (log sin (x))-1 <= sinx <= +1log a is defined by the positive values ​​of a, log sin (x) defined sin (x) = (0,1] Possible values ​​for log sin (x) = (−∞, 0] Log domain (log sin (x)) = Unspecified. Therefore, option (C) is correct.

Question 4

The following paradigm can be used to find the solution of the problem in minimum time: Given a set of non-negative integer, and a value K, determine if there is a subset of the given set with sum equal to K:

• A. Divide and Conquer
• B. Dynamic Programming
• C. Greedy Algorithm
• D. Branch and Bound

Answer: (B)

ISRO CS 2018 Dynamic Programming
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Given problem is Subset-sum problem in which a set of non-negative integers, and a value sum is given, to determine if there is a subset of the given set with sum equal to given sum. With recursion technique, time complexity of the above problem is exponential. We can solve the problem in Pseudo-polynomial time using Dynamic programming. Refer: Subset Sum Problem Option (B) is correct

Question 5

( G, *) is an abelian group. Then

• A. x = x ^-1, for any x belonging to G
• B. x = x², for any x belonging to G
• C. (x * y )² = x² * y², for any x, y belonging to G
• D. G is of finite order

Answer: (C)

ISRO CS 2018 Set Theory & Algebra
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Question 6

Consider the following C code segment:

#include 
main()
{
    int i, j , x ;
    scanf("%d", &x);
    i = 1 ; j = 1;
    while ( i< 10 ) {
          j = j * i;
          i = i + 1;
          if (i == x) break ;
          }
 }

For the program fragment above, which of the following statements about the variables i and j must be true after execution of this program? [!(exclamation) sign denotes factorial in the answer]

• A. ( j = (x - 1 )! ) ∧ (i >= x)
• B. ( j = 9!) ∧ (i =10)
• C. (( j = 10!) ∧ (i = 10 )) V (( j = (x - 1)!) ∧ (i = x ))
• D. (( j = 9!) ∧ (i = 10)) V (( j = (x - 1)!) ∧ (i = x ))

Answer: (D)

ISRO CS 2018 C Loops & Control Structure
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Question 7

A computer uses ternary system instead of the traditional binary system. An n bit string in the binary system will occupy

• A. 3 + n ternary digits
• B. 2n / 3 ternary digits
• C. n(log₂3) ternary digits
• D. n(log₃2 ) ternary digits

Answer: (D)

ISRO CS 2018 Computer Organization and Architecture Secondary memory and DMA
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Question 8

Which of the following is application of Breath First Search on the graph?

• A. Finding diameter of the graph
• B. Finding bipartite graph
• C. Both (a) and (b)
• D. None of the above

Answer: (C)

ISRO CS 2018 Graph Shortest Paths
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BFS is used to Find the diameter of the graph and to test whether a graph is bipartite or not. BFS has many other applications also. Refer: Applications of Breadth First Traversal Option (C) is correct.

Question 9

Micro program is

• A. the name of a source program in micro computers
• B. set of micro instructions that defines the individual operations in response to a machine-language instruction
• C. a primitive form of macros used in assembly language programming
• D. a very small segment of machine code

Answer: (B)

ISRO CS 2018 Computer Organization and Architecture Secondary memory and DMA
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Question 10

Given two sorted list of size m and n respectively. The number of comparisons needed the worst case by the merge sort algorithm will be

• A. m x n
• B. maximum of m and n
• C. minimum of m and n
• D. m + n - 1

Answer: (D)

ISRO CS 2018 MergeSort
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To merge two lists of size m and n, we need to do m+n-1 comparisons in worst case. Since we need to merge 2 at a time, the optimal strategy would be to take smallest size lists first. The reason for picking smallest two items is to carry minimum items for repetition in merging. So, option (D) is correct.