Lemyte

GATE 2015 CS (Set 3) question paper PDF and answer key

The official GATE 2015 Computer Science & Information Technology (Set 3) paper, organised by IIT Kanpur: 65 questions for 100 marks in 3 hours. Download the official question paper and answer key as PDFs. Below is how the marks were split by topic, the complete official answer key and 5 questions solved step by step.

Take this paper as a timed testTry the free demo
Question paper (PDF)Official answer key (PDF)

Source: the official paper and answer key published by IIT Kanpur for GATE 2015. Spotted a mistake? Email team@lemyte.com.

General Aptitude
10 · 15 marks
Computer Science & Information Technology
55 · 85 marks
MCQ / MSQ / NAT
45 / 0 / 20
Marks to all
None

Where the marks were

GATE 2015 CS (Set 3) topic-wise marks

Computer Science & Information Technology questions only; General Aptitude adds 15 marks on top. The top three topics carried 36 of the 85 subject marks.

TopicQuestionsMarks
Programming and Data Structures1318
Computer Networks69
Algorithms59
Discrete Mathematics57
Computer Organization and Architecture47
Databases46
Operating System46
Digital Logic35
Calculus35
Theory of Computation35
Linear Algebra23
Compiler Design23
Probability and Statistics12

Free solved questions

5 solved questions from GATE 2015 CS (Set 3)

Question text and figures as in the official paper, the answer from the official key, and a worked solution. The other 60 solutions are in your report after you take the paper.

Q6 · General Aptitude · MCQ · 2 marks

Alexander turned his attention towards India, since he had conquered Persia.

Which one of the statements below is logically valid and can be inferred from the above sentence?

  • (A)
    Alexander would not have turned his attention towards India had he not conquered Persia.
  • (B)
    Alexander was not ready to rest on his laurels, and wanted to march to India.
  • (C)
    Alexander was completely in control of his army and could command it to move towards India.
  • (D)
    Since Alexander's kingdom extended to Indian borders after the conquest of Persia, he was keen to move further.

Answer (official key): A

Solution

The sentence gives conquest of Persia as the reason for Alexander turning his attention towards India. Among the options, only Option A captures this conditional dependence.

Therefore, the correct answer is Option A.

Q7 · General Aptitude · MCQ · 2 marks

Most experts feel that in spite of possessing all the technical skills required to be a batsman of the highest order, he is unlikely to be so due to lack of requisite temperament. He was guilty of throwing away his wicket several times after working hard to lay a strong foundation. His critics pointed out that until he addressed this problem, success at the highest level will continue to elude him.

Which of the statement(s) below is/are logically valid and can be inferred from the above passage?

(i) He was already a successful batsman at the highest level.
(ii) He has to improve his temperament in order to become a great batsman.
(iii) He failed to make many of his good starts count.
(iv) Improving his technical skills will guarantee success.

  • (A)
    (iii) and (iv)
  • (B)
    (ii) and (iii)
  • (C)
    (i), (ii) and (iii)
  • (D)
    (ii) only

Answer (official key): B

Solution

The passage says he has the technical skill but lacks temperament. Therefore, he must improve temperament to succeed at the highest level. It also says he threw away his wicket after building strong foundations, meaning he failed to convert good starts.

So statements (ii) and (iii) are valid.

Therefore, the correct answer is Option B.

Q36 · Operating System · MCQ · 2 marks

Consider the following policies for preventing deadlock in a system with mutually exclusive resources.

I. Processes should acquire all their resources at the beginning of execution. If any resource is not available, all resources acquired so far are released.
II. The resources are numbered uniquely, and processes are allowed to request resources only in increasing resource numbers.
III. The resources are numbered uniquely, and processes are allowed to request resources only in decreasing resource numbers.
IV. The resources are numbered uniquely. A process is allowed to request only for a resource with resource number larger than its currently held resources.

Which of the above policies can be used for preventing deadlock?

  • (A)
    Any one of I and III but not II or IV
  • (B)
    Any one of I, III and IV but not II
  • (C)
    Any one of II and III but not I or IV
  • (D)
    Any one of I, II, III and IV

Answer (official key): D

Solution

Each listed policy prevents at least one necessary condition for deadlock, especially circular wait or hold-and-wait.

Therefore, the correct answer is Option D.

Q37 · Probability and Statistics · Numerical · 2 marks

Suppose XiX_i for i=1,2,3i=1,2,3 are independent and identically distributed random variables whose probability mass functions are

Pr[Xi=0]=Pr[Xi=1]=12Pr[X_i=0] = Pr[X_i=1] = \frac{1}{2}

for i=1,2,3i=1,2,3. Define another random variable

Y=X1X2⊕X3,Y = X_1X_2 \oplus X_3,

where ⊕\oplus denotes XOR. Then

Pr[Y=0∣X3=0]=Pr[Y=0 \mid X_3=0] =

__________.

Answer (official key): 0.75

Solution

Given X3=0X_3=0,

Y=X1X2⊕0=X1X2.Y=X_1X_2 \oplus 0 = X_1X_2.

So Y=0Y=0 unless both X1=1X_1=1 and X2=1X_2=1.

Thus:

Pr(Y=0∣X3=0)=1−14=34=0.75.Pr(Y=0\mid X_3=0)=1-\frac{1}{4}=\frac{3}{4}=0.75.

Therefore, the answer is 0.75.

Q38 · Compiler Design · MCQ · 2 marks

Consider the following grammar GG:

S→F∣HS \to F \mid H F→p∣cF \to p \mid c H→d∣cH \to d \mid c

where S,F,HS,F,H are non-terminal symbols, and p,d,cp,d,c are terminal symbols. Which of the following statement(s) is/are correct?

S1. LL(1) can parse all strings that are generated using grammar GG.
S2. LR(1) can parse all strings that are generated using grammar GG.

  • (A)
    Only S1
  • (B)
    Only S2
  • (C)
    Both S1 and S2
  • (D)
    Neither S1 nor S2

Answer (official key): D

Solution

Both FF and HH can derive terminal c, creating ambiguity in choosing between productions from SS. The grammar is not suitable for LL(1), and as given, the accepted answer marks neither LL(1) nor LR(1) as able to parse all generated strings.

Therefore, the correct answer is Option D.

The other 60 questions are solved in your report when you take GATE 2015 CS (Set 3) as a 3-hour test.

Take GATE 2015 CS (Set 3) as a test

Official answer key

GATE 2015 CS (Set 3) answer key

All 65 answers from the official key. Numerical answers are ranges; “or” means the key accepts either answer.

Download the official GATE 2015 CS (Set 3) answer key (PDF)
QTopicTypeMarksAnswer
1Verbal AptitudeMCQ1B
2Verbal AptitudeMCQ1C
3Quantitative AptitudeMCQ1C
4Analytical AptitudeMCQ1B
5Verbal AptitudeMCQ1B
6Analytical AptitudeMCQ2A
7Analytical AptitudeMCQ2B
8Analytical AptitudeMCQ2B
9Quantitative AptitudeNumerical22006
10Quantitative AptitudeMCQ2B
11Discrete MathematicsMCQ1A
12Programming and Data StructuresNumerical1612 to 613
13Digital LogicMCQ1B
14Discrete MathematicsNumerical115
15CalculusMCQ1A
16Theory of ComputationMCQ1B
17Computer Organization and ArchitectureMCQ1A
18Computer NetworksMCQ1D
19Programming and Data StructuresNumerical128
20Programming and Data StructuresNumerical1199
21Programming and Data StructuresMCQ1A
22Programming and Data StructuresMCQ1C
23Linear AlgebraMCQ1B
24Programming and Data StructuresMCQ1B
25Computer NetworksMCQ1B
26DatabasesMCQ1A
27AlgorithmsMCQ1C
28Compiler DesignMCQ1C
29Operating SystemMCQ1D
30Operating SystemMCQ1A
31Programming and Data StructuresMCQ1D
32Programming and Data StructuresNumerical180
33DatabasesMCQ1C
34Computer NetworksMCQ1A
35Discrete MathematicsMCQ1D
36Operating SystemMCQ2D
37Probability and StatisticsNumerical20.75
38Compiler DesignMCQ2D
39DatabasesNumerical250
40Computer Organization and ArchitectureNumerical23
41AlgorithmsMCQ2B
42DatabasesMCQ2B
43Theory of ComputationMCQ2C
44Computer Organization and ArchitectureMCQ2B
45Discrete MathematicsNumerical25
46Theory of ComputationMCQ2B
47Computer NetworksNumerical2158
48CalculusMCQ2A
49AlgorithmsNumerical20
50Computer NetworksNumerical21575
51Linear AlgebraMCQ2C
52AlgorithmsNumerical2995
53Digital LogicNumerical23
54Digital LogicMCQ2A
55Programming and Data StructuresNumerical210
56AlgorithmsMCQ2D
57Operating SystemMCQ2C
58Programming and Data StructuresNumerical2140
59Computer NetworksNumerical28
60Programming and Data StructuresMCQ2B
61Programming and Data StructuresNumerical2230
62Computer Organization and ArchitectureMCQ2C
63Discrete MathematicsMCQ2C
64CalculusNumerical2308 to 310
65Programming and Data StructuresMCQ2A

Questions about GATE 2015 CS (Set 3)

How many questions are in the GATE 2015 CS (Set 3) paper?

65 questions for 100 marks: 10 General Aptitude questions worth 15 marks and 55 Computer Science & Information Technology questions worth 85 marks. By type, there were 45 MCQs, 20 numerical answer (NAT) questions. The paper lasted 3 hours.

Is there negative marking in GATE 2015 CS (Set 3)?

Yes, for MCQs only. A wrong MCQ answer costs one-third of its marks (−⅓ for a 1-mark question, −⅔ for a 2-mark question). MSQ and numerical (NAT) questions have no negative marking, and an MSQ earns marks only when every correct option is chosen.

Which topics carried the most marks in GATE 2015 CS (Set 3)?

Outside General Aptitude, the biggest topics were Programming and Data Structures (18 marks), Computer Networks (9 marks), Algorithms (9 marks). The full topic-wise split is in the table on this page.

Were any GATE 2015 CS (Set 3) questions awarded marks to all?

No. Every question was graded with the answer in the official key.

Where does this GATE 2015 CS (Set 3) answer key come from?

From the official answer key published by IIT Kanpur, which organised GATE 2015. Range answers for numerical questions and questions with more than one accepted answer are kept exactly as the key gives them.

More GATE papers