Detailed Solutions
COMPUTER
ISRO SCIENCE
Written Test of Scientist/Engineer Examination
Date of Test : 12-01-2020
Set-E
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typo/technical error, kindly mail us at:
• Students are requested to share their expected marks.
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, ISRO : Computer Science
Detailed Solutions : Exam held on 12.01.2020
ISRO (Scientist/Engineer) Examination
Computer Science : Paper Analysis
Exam held on 12.01.2020
Sl. Subjects No. of Qs. Level of Difficulty
1 Programming and Data Structures 16 Moderate to high
2 Digital Logic 8 Moderate to high
3 Algorithms 5 Moderate
4 Operating System 9 Easy to moderate
5 Computer Networks 5 Easy
6 Databases 4 Moderate
7 Computer organization and 13 High
Architecture
8 Software Engineering and others 9 Easy to moderate
9 Discrete Mathematics 4 Easy
10 Theory of Computation 7 Easy
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, ISRO : Computer Science
Detailed Solutions : Exam held on 12.01.2020
Q.1 Regression testing is primarily related to
(a) Functional testing (b) Development testing
(c) Data flow testing (d) Maintenance testing
Ans. (a)
The purpose of regression testing is to select test cases partially or fully to ensure
existing functionalities works fine. Thus, regression testing is primarily related to functional
testing.
End of Solution
Q.2 Of the following sort algorithms, which has execution time that is least dependant on
initial ordering of the input?
(a) Insertion sort (b) Quick sort
(c) Merge sort (d) Selection sort
Ans. (c)
Insertion sort gives Ο(n) time when inputs are already sorted.
Quick sort gives Ο(n2) time when inputs are almost sorted.
Merge sort is independent of initial ordering and always gives Ο(n log n)
Select sort gives Ο(n2) always but if elements are always sorted, number of swaps will
be less.
End of Solution
Q.3 The following circuit compares two 2-bit binary numbers, X and Y represented by X1X0
and Y1Y0 respectively. (X0 and Y0 represent Least Significant Bits)
X1 Y1 X0 Y0
Z
Under what condition Z will be 1?
(a) X > Y (b) X < Y
(c) X = Y (d) X ! = Y
Ans. (a)
Z = X1Y + (X1 Y1)X0Y0
If X > Y, then Z=1
End of Solution
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, ISRO : Computer Science
Detailed Solutions : Exam held on 12.01.2020
Q.4 What is the availability of the software with following reliability figures.
Mean Time Between Failures (MTBF) is 20 days
Mean Time To Repair (MTTR) is 20 hours.
(a) 90% (b) 96%
(c) 24% (d) 50%
Ans. (d)
MTBF ⎛ 20 ⎞
Software availability = = ⎜ ⎟ = 50%
(MTBF + MTTR) ⎝ 20 + 20 ⎠
End of Solution
Q.5 What is the defect rate for Six sigma?
(a) 1.0 defect per million lines of code
(b) 1.4 defects per million lines of code
(c) 3.0 defects per million lines of code
(d) 3.4 defects per million lines of code
Ans. (d)
End of Solution
Q.6 Consider a 5-segment pipeline with a clock cycle time 20 ns in each sub operation. Find
out the approximate speed-up ratio between pipelined and non-pipelined system to
execute 100 instructions. (If an average, every five cycles, a bubble due to data hazard
has to be introduced in the pipeline)
(a) 5 (b) 4.03
(c) 4.81 (d) 4.17
Ans. (b)
K =5
Clock time = 20 ns
Number of instructions = 100
Number of cycles taken by non-pipelined processor = 100 × 5 = 500
100 ⎡100 ⎤
Total inputs in the pipeline = 100 + = 120 ⎢ = 20 stalls⎥
5 ⎣ 5 ⎦
(5 × 100) × 20 ns
Speed up = = 4.03
(5 + 120 − 1) × 20 ns
End of Solution
Q.7 Consider a 32-bit processor which supports 70 instructions. Each instruction is 32 bit
long and has 4 fields namely opcode, two register identifiers and an immediate operand
of unsigned integer type. Maximum value of the immediate operand that can be supported
by the processor is 8191. How many registers the processor has?
(a) 32 (b) 64
(c) 128 (d) 16
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COMPUTER
ISRO SCIENCE
Written Test of Scientist/Engineer Examination
Date of Test : 12-01-2020
Set-E
• MADE EASY has taken due care in making solutions. If you find any discrepency/
typo/technical error, kindly mail us at:
• Students are requested to share their expected marks.
www.madeeasy.in
Corporate Office: 44-A/1, Kalu Sarai, New Delhi - 110016 | Ph: 011-45124612, 9958995830
Delhi | Hyderabad | Noida | Bhopal | Jaipur | Lucknow | Indore | Pune | Bhubaneswar | Kolkata | Patna
, ISRO : Computer Science
Detailed Solutions : Exam held on 12.01.2020
ISRO (Scientist/Engineer) Examination
Computer Science : Paper Analysis
Exam held on 12.01.2020
Sl. Subjects No. of Qs. Level of Difficulty
1 Programming and Data Structures 16 Moderate to high
2 Digital Logic 8 Moderate to high
3 Algorithms 5 Moderate
4 Operating System 9 Easy to moderate
5 Computer Networks 5 Easy
6 Databases 4 Moderate
7 Computer organization and 13 High
Architecture
8 Software Engineering and others 9 Easy to moderate
9 Discrete Mathematics 4 Easy
10 Theory of Computation 7 Easy
Corporate Office: 44-A/1, Kalu Sarai, New Delhi-110016 | | ß www.madeeasy.in Page 2
, ISRO : Computer Science
Detailed Solutions : Exam held on 12.01.2020
Q.1 Regression testing is primarily related to
(a) Functional testing (b) Development testing
(c) Data flow testing (d) Maintenance testing
Ans. (a)
The purpose of regression testing is to select test cases partially or fully to ensure
existing functionalities works fine. Thus, regression testing is primarily related to functional
testing.
End of Solution
Q.2 Of the following sort algorithms, which has execution time that is least dependant on
initial ordering of the input?
(a) Insertion sort (b) Quick sort
(c) Merge sort (d) Selection sort
Ans. (c)
Insertion sort gives Ο(n) time when inputs are already sorted.
Quick sort gives Ο(n2) time when inputs are almost sorted.
Merge sort is independent of initial ordering and always gives Ο(n log n)
Select sort gives Ο(n2) always but if elements are always sorted, number of swaps will
be less.
End of Solution
Q.3 The following circuit compares two 2-bit binary numbers, X and Y represented by X1X0
and Y1Y0 respectively. (X0 and Y0 represent Least Significant Bits)
X1 Y1 X0 Y0
Z
Under what condition Z will be 1?
(a) X > Y (b) X < Y
(c) X = Y (d) X ! = Y
Ans. (a)
Z = X1Y + (X1 Y1)X0Y0
If X > Y, then Z=1
End of Solution
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, ISRO : Computer Science
Detailed Solutions : Exam held on 12.01.2020
Q.4 What is the availability of the software with following reliability figures.
Mean Time Between Failures (MTBF) is 20 days
Mean Time To Repair (MTTR) is 20 hours.
(a) 90% (b) 96%
(c) 24% (d) 50%
Ans. (d)
MTBF ⎛ 20 ⎞
Software availability = = ⎜ ⎟ = 50%
(MTBF + MTTR) ⎝ 20 + 20 ⎠
End of Solution
Q.5 What is the defect rate for Six sigma?
(a) 1.0 defect per million lines of code
(b) 1.4 defects per million lines of code
(c) 3.0 defects per million lines of code
(d) 3.4 defects per million lines of code
Ans. (d)
End of Solution
Q.6 Consider a 5-segment pipeline with a clock cycle time 20 ns in each sub operation. Find
out the approximate speed-up ratio between pipelined and non-pipelined system to
execute 100 instructions. (If an average, every five cycles, a bubble due to data hazard
has to be introduced in the pipeline)
(a) 5 (b) 4.03
(c) 4.81 (d) 4.17
Ans. (b)
K =5
Clock time = 20 ns
Number of instructions = 100
Number of cycles taken by non-pipelined processor = 100 × 5 = 500
100 ⎡100 ⎤
Total inputs in the pipeline = 100 + = 120 ⎢ = 20 stalls⎥
5 ⎣ 5 ⎦
(5 × 100) × 20 ns
Speed up = = 4.03
(5 + 120 − 1) × 20 ns
End of Solution
Q.7 Consider a 32-bit processor which supports 70 instructions. Each instruction is 32 bit
long and has 4 fields namely opcode, two register identifiers and an immediate operand
of unsigned integer type. Maximum value of the immediate operand that can be supported
by the processor is 8191. How many registers the processor has?
(a) 32 (b) 64
(c) 128 (d) 16
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