Computer Science Previous Year Questions (page 9)

Explanation

The 9001 : 2000 is the quality assurance standard that applies to software engineering. The standard contains 20 requirement that must be present for an effective quality assurance system.

Explanation

External qualities of a software product: - Correctness - Reliability - Robustness - Efficiency - Usability Internal qualities of a software product - Maintainability - Reusability - Portability - Interoperability

Explanation

The <address> tag is used to surround information, such as the signature of the person who created the page or the address of the organization the page is about. The <body> tag defines the document is body. The <em> tag defines emphasized text. The <strong> tag defines important text.

Explanation

Standard JPEG uses the DCT, zig-zag scan, run-length encoding and Huffman coding. The K-L (Karhunen-Loeve) transform is not used in standard JPEG compression.

Explanation

If the histogram of an image is clustered towards the origin (low intensity values) on the X-axis, the image is dark. If it is clustered towards the high end of the X-axis, the image is bright.

Explanation

In Artificial Intelligence, a semantic network is a graph-based method of knowledge representation where nodes represent concepts, instances or events and arcs (links) represent relationships between them, such as is-a, part-of and kind-of.

Explanation

The machine moves right over 0s and accepts on reaching the blank, so it accepts 0*. 00* is a subset of 0*, so the machine accepts all strings of 00*; the only other accepted string is the empty string ε.

Explanation

Each internal node of the derivation tree has exactly k children. The tree is shortest when it is complete, giving h ≥ logₖ |W|, and tallest when each level has only one internal node, giving h ≤ (|W| – 1)/(k – 1). So logₖ |W| ≤ h ≤ (|W| – 1)/(k – 1).

Explanation

Lambda calculus was introduced by Alonzo Church (1932). Its use as a programming language came with LISP by McCarthy (1960). Lazy evaluation was introduced by Wadsworth (1970). Type classes were introduced in Haskell (1990). So A-1, B-4, C-2, D-3.

Explanation

Criticism-free idea generation is a feature of a group decision support system (GDSS).

Explanation

DPCM (differential pulse code modulation) converts the analog source signal into a digital signal, i.e. it is a source coding technique.

Explanation

(0.4051)₈ = 0×8⁰ + 4×8⁻¹ + 0×8⁻² + 5×8⁻³ + 1×8⁻⁴ = 0 + 0.5 + 0 + 0.009765625 + 0.000244140625 = (0.510009765625)₁₀ ≈ 0.5100098

Explanation

(2357)₈ = (010 011 101 111)₂. Grouping into 4 bits from right to left: 0100 1110 1111, so it is (4EF)₁₆.

Explanation

Let x = 2³ = 8 = 1000; then x – 1 = 7 = 0111. Now x & (x – 1) = 0000 (& is bitwise AND: a result bit is 1 only if both compared bits are 1, otherwise 0). So for any power of 2 the result is all zeros.

Explanation

For a 3-bit down counter using J-K flip-flops (in toggle mode): J₀ = K₀ = 1, J₁ = K₁ = Q₀' and J₂ = K₂ = Q₁' Q₀'. So II, IV and VI.

Explanation

Absurd means utterly or obviously senseless, illogical or untrue, i.e. contrary to all reason or evident truth (A–i). Ambiguous means open to more than one meaning or interpretation (B–ii). Axiom is a self-evident truth that requires no proof, a universally accepted principle (C–iii). Conjecture is an opinion or theory formed without sufficient evidence, e.g. based on past experience (D–iv).

Explanation

Given premises (P → Q) ∧ (R → S) and (P ∨ R). (P → Q) = ¬P ∨ Q and (R → S) = ¬R ∨ S. Resolving with P ∨ R, ¬P with P and ¬R with R resolve out, leaving the disjunction Q ∨ S (constructive dilemma). So Q ∨ S is correct.

Explanation

F₀₀(0) = 1, F₀₀(1) = 1. F₀₀(2) = (10*1 + 100)/1 = 110, F₀₀(3) = (10*110 + 100)/1 = 1200, F₀₀(4) = (10*1200 + 100)/110 = 110, F₀₀(5) = (10*110 + 100)/1200 = 1, F₀₀(6) = (10*1 + 100)/110 = 1, and the values repeat. So the set of values is (1, 110, 1200).

Explanation

By Dirac's theorem, deg(v) ≥ n/2 for every vertex; by Ore's theorem, deg(v) + deg(w) ≥ n for every pair of non-adjacent vertices v and w; and a graph with |E(G)| ≥ (1/2)(n – 1)(n – 2) + 2 edges is Hamiltonian. So all of the above.

Explanation

AX consists of AH and AL. mov al, 15 → AX = 000FH mov ah, 15 → AX = 0F0FH xor al, al → AX = 0F00H mov cl, 3 → AX = 0F00H, CL = 03 shr ax, cl → AX = 01E0H (shift right 3 times) add al, 90H → AX = 0170H, carry = 1 adc ah, 0 → AX = 0270H (adds the carry) So AX = 0270H.

Explanation

(AL) = 3AH = 00111010, (BL) = 49H = 01001001. AL – BL = 11110001, so (AL) = F1H, CF = 1, SF = 1. The carry (borrow) flag is set since the first operand is less than the second; the result is negative, so the sign flag is set.

Explanation

Statement B is false: breadth-first search can be used to find the connected components of a graph, just like depth-first search. Optimal binary search tree construction is a well-known dynamic programming application, and given only the prefix and postfix walks of a binary tree, the tree cannot be reconstructed uniquely.

Explanation

Let Xᵢ = 1 if key x collides with the i-th other key, else 0. For a universal hash family, a given pair collides with probability 1/m, so E(Xᵢ) = 1/m. Summing over the other (n – 1) keys, the expected number of collisions involving x is (n – 1)/m. Since n ≤ m, this is less than 1.

Explanation

In a sorted array, insertion and deletion take O(n) in the worst case (elements must be shifted), while the minimum and maximum are always at the two ends, so finding them takes O(1).

Explanation

Data pointer = child pointer + search field value = 7 + 14 = 21 bytes. Maximum number of entries = 1 KB/21 bytes = 1024/21 ≈ 48.76. The book picks 16 since all other options are greater than 48.

Explanation

(A) fails the max-heap property (4 has child 8). (B) is a valid max heap because every parent ≥ its children. (C) fails (1 has child 7). (D) fails (3 has children 9 and 10; 4 has child 8; 1 has child 7).

Explanation

(i) Multiples of 6 between 1 and 100 = ⌊100/6⌋ = 16 (the book counts 16 for 0 to 100). (ii) Multiples of 6 between 0 and 34 = ⌊34/6⌋ + 1 (for 0) = 5 + 1 = 6.

Explanation

p+[3–5]*[xyz] = one or more p, then any number of 3, 4 or 5, then exactly one of x, y, z. (I) p443y → matched (II) p6y → not matched, since 6 cannot be used (III) 3xyz → not matched, string must start with p (IV) p35z → matched (V) p353535x → matched (VI) ppp5 → not matched, string must end with x, y or z

Explanation

Statement I is true: a linker combines several object modules into a single load module. Statement II is wrong: a linker replaces symbolic references by addresses (it generates relocatable addresses), not absolute references by symbolic ones.

Explanation

Initial value S = 1. (1) P2 needs to access: S = 0 (no one waiting) (2) P1 needs to access: S = –1 (one process waiting) (3) P3 needs to access: S = –2 (two processes waiting) (4) P2 exits critical section: S = –1 (one process waiting) (5) P1 exits critical section: S = 0 (no process waiting)

Explanation

TLB hit ratio 70%, TLB search 30 ns, memory access 90 ns. On a hit, the page is found in the TLB (30 ns); on a miss, the TLB is searched and the page table read from memory (30 + 90 ns); then 90 ns to access the data. Total = (0.7 × 30) + (0.3 × (90 + 30)) + 90 = 21 + 36 + 90 = 147 ns

Explanation

The correct match: A. Device controller – i. Extracts information from the controller register and stores it in data buffer; B. Device driver – iii. Performs data transfer; C. Interrupt handler – iv. Processing of I/O request; D. Kernel I/O subsystem – ii. I/O scheduling.

Explanation

(1) First come – first served – No starvation (2) Round robin – No starvation (3) Priority – starvation if higher priority process called again & again lower priority starves (4) Shortest process next = starvation possible (5) Shortest remaining time first = starvation possible

Explanation

A distributed operating system is usually defined as running on more loosely coupled hardware. There is no shared memory, but provides a single memory by tightly coupled software.

Explanation

The practice of examining large pre-existing databases in order to generate new information is data mining. It refers loosely to the process of semi-automatically analyzing large databases to find useful patterns.

Explanation

(1) ERP automates and integrates majority of business – true (2) ERP provides access to information in a real time environment – true (3) ERP is inexpensive to implement – false

Explanation

CHAR and VARCHAR are both declared with a maximum length, but a CHAR column is fixed to the declared length (padded with spaces), while VARCHAR(20) uses only as much space as the stored value. So A ('Ram') needs 3 spaces and B ('Sita') needs 20.

Explanation

An instructor Id. No. cannot be null when it is the primary key – valid integrity constraint. No two citizens have the same Aadhaar-Id – valid. But 'the budget of a company must be zero' is not a valid integrity constraint. So (A) and (B) are true and (C) is false.

Explanation

Two tables are created for entities M and N, and a third table for the many-to-many relationship R₂. R₁ (one-to-many) needs no separate table: the primary key of the 'one' side is placed as a foreign key in the 'many' side. So the minimum is 3 tables.

Explanation

With R(MNPQ), M → N and P → Q, the decomposition into R₁(MN) and R₂(PQ) clearly preserves both dependencies, but it is not lossless because R₁ and R₂ have no common attribute, so R cannot be recovered by joining them.

Explanation

The correct match: A. Application layer – iv. HTTP; B. Transport layer – i. TCP; C. Network layer – ii. IP; D. Datalink layer – iii. PPP.

Explanation

Default gateway serves an access point or IP router that a networked uses to send information to a computer in another network or the internet. Default simply means that this gateway is used by default, unless an application specifies another gateway.

Explanation

A distance vector routing protocol requires that a router inform its neighbors about its topology changes periodically.

Explanation

Software engineering is an engineering discipline that is concerned with all aspects of software production.

Explanation

This model allows for the creation of a preliminary version (prototype) of the software, which can be refined iteratively based on user feedback until satisfactory version is achieved. Clarifies Requirements– The prototyping process helps customers visualize and understand what the final product will look like and how it will function. Reduce Risk– By identifying potential issues early on through prototyping, developers can avoid costly rework and delays later in the development cycle.

Explanation

Mccalls's software quality factors. (1) ability to undergo change (2) Adaptability to new environments (3) Operational characteristics but production costs & scheduling is not the aspect of quality factor.

Explanation

S1 and S2 swap the definitions: cohesion measures how well the things grouped in a module belong together, and coupling measures the degree of interaction between modules. S3 is true: if coupling is low and cohesion is high, it is easier to change one module without affecting others.

Explanation

In object-oriented programming, the decorator pattern (also known as wrapper) is a design pattern that allows behaviour to be added to an individual object, statically or dynamically at run-time, without affecting the behaviour of other objects of the same class.

Explanation

extern declares variables/functions with external linkage, giving them global visibility across files. It is the default storage class of all global variables and functions.

Explanation

Structure reference refers to the dot operator (.), which is one of the operators that cannot be overloaded in C++. The other options (>>=, unary & and unary *) can be overloaded for custom types in C++.