GATE CSE topic:computing PYQs & Answers — Page 52

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Questions 511–520 of 975. Imported answers require independent review unless marked reviewed.

Topic practice 975 questionsPage 52 of 98

Consider the relational database with the following four schemas and their respective instances.

Student (sNo, sName, dNo) | Dept (dNo, dName) Course (cNo, cName, dNo) | Register (sNo, cNo)

Student

sNo	sName	dNo
S01	James	D01
S02	Rocky	D01
S03	Jackson	D02
S04	Jane	D01
S05	Milli	D02

Dept

dNo	dName
D01	CSE
D02	EE

Course

cNo	cName	dNo
C11	DS	D01
C12	OS	D01
C21	DE	D02
C22	PT	D02
C23	CV	D03

sNo	cNo
S01	C11
S01	C12
S02	C11
S03	C21
S03	C22
S03	C23
S04	C11
S04	C12
S05	C11
S05	C21

SQL Query:

SELECT * FROM Student AS S WHERE NOT EXIST (SELECT cNo FROM Course WHERE dNo = “D01” EXCEPT SELECT cNo FROM Register WHERE sNo = S.sNo)

The number of rows returned by the above SQL query is __________.

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Consider a network with three routers P, Q, R shown in the figure below. All the links have cost of unity.

Diagram for Computer Science and Information Technology question 57

The routers exchange distance vector routing information and have converged on the routing tables, after which the link Q–R fails. Assume that P and Q send out routing updates at random times, at the same average rate. The probability of a routing loop forming (rounded off to one decimal place) between P and Q, leading to count-to-infinity problem, is __________.

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Let

be a directed graph, where

is the set of vertices and

is the set of directed edges, as defined by the following adjacency matrix

indicates a directed edge from node

to node

. A directed spanning tree of

, rooted at

, is defined as a subgraph

such that the undirected version of

is a tree, and

contains a directed path from

to every other vertex in

. The number of such directed spanning trees rooted at vertex 5 is __________.

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Consider a 100 Mbps link between an earth station (sender) and a satellite (receiver) at an altitude of 2100 km. The signal propagates at a speed of

m/s. The time taken (in milliseconds, rounded off to two decimal places) for the receiver to completely receive a packet of 1000 bytes transmitted by the sender is __________.

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Consider the data transfer using TCP over a 1 Gbps link. Assuming that the maximum segment lifetime (MSL) is set to 60 seconds, the minimum number of bits required for the sequence number field of the TCP header, to prevent the sequence number space from wrapping around during the MSL is __________.

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A processor X₁ operating at 2 GHz has a standard 5-stage RISC instruction pipeline having a base CPI (cycles per instruction) of one without any pipeline hazards. For a given program P that has 30% branch instructions, control hazards incur 2 cycles stall for every branch. A new version of the processor X₂ operating at same clock frequency has an additional branch predictor unit (BPU) that completely eliminates stalls for correctly predicted branches. There is neither any savings nor any additional stalls for wrong predictions. There are no structural hazards and data hazards for X₁ and X₂. If the BPU has a prediction accuracy of 80%, the speed up (rounded off to two decimal places) obtained by X₂ over X₁ in executing P is __________.

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Consider the queues

containing four elements and

containing none (shown as the Initial State in the figure). The only operations allowed on these two queues are Enqueue (Q, element) and Dequeue (Q). The minimum number of Enqueue operations on

required to place the elements of

in reverse order (shown as the Final State in the figure) without using any additional storage is __________.

Diagram for Computer Science and Information Technology question 62

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Consider two file systems

and

, that use contiguous allocation and linked allocation, respectively. A file of size 100 blocks is already stored in A and also in B. Now, consider inserting a new block in the middle of the file between the 50ᵗʰ and 51ˢᵗ block, whose data is already available in the memory. Assume that there are enough free blocks at the end of the file and that the file control blocks are already in memory. Let the number of disk accesses required to insert a block in the middle of the file in

and

are

and

, respectively, then the value of

is __________.

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Consider a demand paging system with four page frames (initially empty) and LRU page replacement policy. For the following page reference string

7, 2, 7, 3, 2, 5, 3, 4, 6, 7, 1, 5, 6, 1

the page fault rate, defined as the ratio of number of page faults to the number of memory accesses (rounded off to one decimal place) is __________.

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Consider the following grammar along with translation rules.

Here # and % are operators and

is a token that represents an integer and

represents the corresponding integer value. The set of non-terminals is

and a subscripted non-terminal indicates an instance of the non-terminal.

Using this translation scheme, the computed value of

for root of the parse tree for the expression

is __________.

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GATE CSE topic:computing PYQs

Question 56

Question 57

Question 58

Question 59

Question 60

Question 61

Question 62

Question 63

Question 64

Question 65

sNo	cNo
S01	C11
S01	C12
S02	C11
S03	C21
S03	C22
S03	C23
S04	C11
S04	C12
S05	C11
S05	C21

sNo	cNo
S01	C11
S01	C12
S02	C11
S03	C21
S03	C22
S03	C23
S04	C11
S04	C12
S05	C11
S05	C21

sNo	cNo
S01	C11
S01	C12
S02	C11
S03	C21
S03	C22
S03	C23
S04	C11
S04	C12
S05	C11
S05	C21