Computer Science and Information Technology
GATE CSE format:nat PYQs
Build your understanding with focused practice from past exam papers.
Questions 241–250 of 281. Imported answers require independent review unless marked reviewed.
Question 55
Open questionCSNAT2 marksNeeds review
Consider a simple communication system where multiple nodes are connected by a shared broadcast medium (like Ethernet or wireless). The nodes in the system use the following carrier-sense based medium access protocol. A node that receives a packet to transmit will carrier-sense the medium for 5 units of time. If the node does not detect any other transmission in this duration, it starts transmitting its packet in the next time unit. If the node detects another transmission, it waits until this other transmission finishes, and then begins to carrier-sense for 5 time units again. Once the start to transmit, nodes do not perform any collision detection and continue transmission even if a collision occurs. All transmissions last for 20 units of time. Assume that the transmission signal travels at the speed of 10 meters per unit time in the medium.
Assume that the system has two nodes P and Q, located at a distance d meters from each other. P starts transmitting a packet at time t=0 after successfully completing its carrier-sense phase. Node Q has a packet to transmit at time t=0 and begins to carrier-sense the medium.
The maximum distance d (in meters, rounded to the closest integer) that allows Q to successfully avoid a collision between its proposed transmission and P’s ongoing transmission is _____.
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Open questionCSNAT1 markNeeds review
Let X be a Gaussian random variable with mean 0 and variance σ². Let Y = max(X, 0) where max(a, b) is the maximum of a and b. The median of Y is __________.
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Open questionCSNAT1 markNeeds review
Consider the following tables T1 and T2.
T1:
P | Q |
|---|---|
2 | 2 |
3 | 8 |
7 | 3 |
5 | 8 |
6 | 9 |
8 | 5 |
9 | 8 |
T2:
R | S |
|---|---|
2 | 2 |
8 | 3 |
3 | 2 |
9 | 7 |
5 | 7 |
7 | 2 |
In table T1, P is the primary key and Q is the foreign key referencing R in table T2 with on-delete cascade and on-update cascade. In table T2, R is the primary key and S is the foreign key referencing P in table T1 with on-delete set NULL and on-update cascade. In order to delete record (3, 8) from table T1, the number of additional records that need to be deleted from table T1 is __________.
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Open questionCSNAT1 markNeeds review
Let T be a tree with 10 vertices. The sum of the degrees of all the vertices in T is __________.
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Open questionCSNAT1 markNeeds review
The maximum number of IPv4 router addresses that can be listed in the record route (RR) option field of an IPv4 header is __________.
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Open questionCSNAT1 markNeeds review
Consider the Karnaugh map given below, where X represents “don’t care” and blank represents 0.
Karnaugh map columns labelled
: 00, 01, 11, 10; rows labelled
: 00, 01, 11, 10. Cell values: row 00: blank, X, X, blank; row 01: 1, blank, blank, X; row 11: 1, blank, blank, 1; row 10: blank, X, X, blank. 
Assume for all inputs
, the respective complements
are also available. The above logic is implemented using 2-input NOR gates only. The minimum number of gates required is ____________.Log in to check the answer
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Open questionCSNAT1 markNeeds review
Consider the set
under the partial ordering
.
The Hasse diagram of the partial order
is shown below. 
The minimum number of ordered pairs that need to be added to
to make
a lattice is __________.Log in to check the answer
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Open questionCSNAT1 markNeeds review
Consider the language
given by the regular expression
over the alphabet
. The smallest number of states needed in a deterministic finite-state automaton (DFA) accepting
is ____________.Log in to check the answer
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Open questionCSNAT1 markNeeds review
Let
and
be two matrices.
Then the rank of
is __________.Log in to check the answer
You can attempt this question now. Sign in to view the answer key, explanations and discussion.Log in to check answerQuestion 23
Open questionCSNAT1 markNeeds review
Consider a database that has the relation schema EMP (EmpId, EmpName, and DeptName). An instance of the schema EMP and a SQL query on it are given below.
EMP:
EmpId | EmpName | DeptName |
|---|---|---|
1 | XYA | AA |
2 | XYB | AA |
3 | XYC | AA |
4 | XYD | AA |
5 | XYE | AB |
6 | XYF | AB |
7 | XYG | AB |
8 | XYH | AC |
9 | XYI | AC |
10 | XYJ | AC |
11 | XYK | AD |
12 | XYL | AD |
13 | XYM | AE |
SQL:
SELECT AVG(EC.Num)
FROM EC
WHERE (DeptName, Num) IN
(SELECT DeptName, COUNT(EmpId) AS
EC(DeptName, Num)
FROM EMP
GROUP BY DeptName)
The output of executing the SQL query is ____________.
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