DSSSB TGT Computer Science PYQ (Technical), 8 Aug 2021, Shift 2

Explanation

Every row of the second matrix is 2 times the corresponding row of the first. Multiplying all three rows of a 3×3 matrix by 2 multiplies the determinant by 2³ = 8, so the new determinant is 8 × (−p) = −8p.

Explanation

byx = (nΣxy − ΣxΣy) / (nΣy² − (Σy)²) = (5×41 − 12×12) / (5×45 − 144) = (205 − 144) / (225 − 144) = 61/81. Since Σx² = Σy², both denominators give the same value.

Explanation

The chance that all four shots miss is 0.4 × 0.5 × 0.6 × 0.8 = 0.096. So P(at least one hit) = 1 − 0.096 = 0.904.

Explanation

Under the Companies Act, a public limited company needs at least 7 members (shareholders). A private company needs only 2.

Explanation

Ctrl + H opens the Find and Replace dialog in MS Word. Ctrl + R right-aligns text, Ctrl + D opens the Font dialog and Ctrl + A selects all.

Explanation

FORTRAN stands for FORmula TRANslation. It was developed by IBM in the 1950s for scientific and mathematical computing.

Explanation

The kernel is the core of the OS. It stays resident in main memory and manages the CPU, memory and devices. Other OS parts can be loaded only when needed.

Explanation

Perl is a scripting language that is normally interpreted. C is a compiled language: source code is turned into machine code before it runs.

Explanation

The three pillars of object-oriented programming are encapsulation, inheritance and polymorphism, so a language must support all three.

Explanation

Rows run from −4 to 1, which is 1 − (−4) + 1 = 6 rows. Columns run from 6 to 10, which is 10 − 6 + 1 = 5 columns. Total elements = 6 × 5 = 30.

Explanation

A stack holds pending work in LIFO order. The postponed items wait on the stack and are processed only after the current conditions are met, as in recursion or backtracking.

Explanation

Quick sort's worst case happens when the pivot is always the smallest or largest element, for example on already sorted input. Each partition then removes only one element, giving Θ(n²).

Explanation

Polish notation is prefix notation. (A*B + C) becomes +*ABC and (E − F*G) becomes −E*FG. Dividing the first by the second gives /+*ABC−E*FG.

Explanation

++v makes v = 9 before the division. Then i = 8/9 = 0 because integer division drops the fraction. printf prints 0 (followed by the literal text "/n").

Explanation

This new-order is right, node, left, which is reverse in-order. The right subtree of P gives Z, V, Y, X, W. Then comes P. The left subtree gives S, U, T, Q, R.

Explanation

14 has two children, so it is replaced by its in-order successor 16, the smallest key in its right subtree. 16's right child 20 moves up. Pre-order is then 16, 10, 7, 13, 11, 20, 18, 25, 22.

Explanation

short a[5] takes 5 × 2 = 10 bytes. The union takes the size of its largest member, long, which is 8 bytes. Total = 10 + 8 = 18 bytes, ignoring alignment padding.

Explanation

XMODEM is a simple file-transfer protocol for uploading and downloading files between computers over modems. It sends data in 128-byte blocks with a checksum.

Explanation

A network operating system, such as Windows Server or Novell NetWare, lets computers on a network share files, printers and other resources.

Explanation

In half duplex, data can travel in both directions but only one way at a time, like a walkie-talkie. Full duplex allows both directions at once, and simplex allows only one direction.

Explanation

An OMR (Optical Mark Reader) senses marks shaded in fixed positions, so it is used to read answers on objective tests and survey forms.

Explanation

A dot-matrix printer forms characters by pins striking an inked ribbon against the paper, so it is an impact printer. Inkjet, laser and thermal printers are non-impact printers.

Explanation

Magnetic tape is a sequential-access device, not a direct-access one, so statement I is false. It does store large volumes of data cheaply and is widely used for backup.

Explanation

The light is on only when the two inputs differ, which is exactly the XOR truth table: 0,0→0; 1,1→0; 0,1 or 1,0→1.

Explanation

A twisted ring counter, also called a Johnson counter, feeds the complement of the last flip-flop's output back to the D input of the first stage. An n-bit Johnson counter has 2n states.

Explanation

For a DAC, linearity error is the largest deviation of the output from the ideal straight line. It is expressed as a percentage of the full-scale, or maximum, output voltage.

Explanation

In Gray code, consecutive numbers differ in exactly one bit, for example 01 → 11 → 10. This is useful in shaft encoders and K-maps.

Explanation

In signed number representation, the most significant bit is the sign bit: 0 means positive and 1 means negative. Both pairs are correct.

Explanation

(21121)₃ = 2×81 + 1×27 + 1×9 + 2×3 + 1 = 205. Converting to base 4: 205 = 3×64 + 0×16 + 3×4 + 1, so the value is (3031)₄.

Explanation

Information processing covers acquiring, storing, organizing, retrieving, displaying and disseminating information.

Explanation

Cardinality is the number of tuples (rows) in a relation, so it is 500. The number of attributes (50) is the degree.

Explanation

E.F. Codd gave 12 rules, numbered 1-12 with an extra Rule 0 (the foundation rule), that a DBMS must satisfy to be called fully relational.

Explanation

Fan traps and chasm traps are the two kinds of connection trap in ER modelling. A fan trap gives ambiguous paths between entities, and a chasm trap gives a missing path.

Explanation

In crow's-foot notation, a single bar means "one". A line with a single bar marks a one-to-one link. A crow's foot means "many", and a circle means "zero" (optional).

Explanation

The recognised database design approaches are top-down, bottom-up, inside-out and mixed. There is no "up-down" approach.

Explanation

COUNT is an aggregate function: it returns one value computed over a set of rows. MINUS, INTERSECT and UNION are set operators.

Explanation

64K = 2¹⁶ words, so 16 address lines are needed. Each word is 8 bits wide, so 8 data lines are needed.

Explanation

1010 ⊕ 1100 = 0110, and this result is stored in R1. R2 is only read, so it stays 1100.

Explanation

The mask (selective clear) micro-operation ANDs bits with a mask, clearing the bits where the mask has 0. So it is equivalent to an AND gate.

Explanation

In indirect addressing, the first memory access reads the operand's effective address and the second fetches the operand itself. That is 2 memory references.

Explanation

ADD R1, A, B names three operands, a destination R1 and two sources A and B (R1 ← A + B), so it is a three-address instruction.

Explanation

The span attribute of <colgroup> or <col> sets how many columns the group covers. Colspan and rowspan are used on table cells (td or th).

Explanation

A bill is dishonoured when the drawee does not pay it on the date of maturity, and it is then recorded as dishonoured in the books.

Explanation

Accounting aims to keep a systematic record of business transactions and to find the profit or loss of the business, along with showing its financial position. Both statements are objectives.

Explanation

Both cause differences. Cheques deposited but not yet collected appear in the cash book but not in the passbook. Interest or dividends collected by the bank appear in the passbook first.

Explanation

Both statements have the measures swapped. Lines of code, execution speed and memory size are direct measures. Functionality, quality and efficiency are indirect measures. So neither statement is correct.

Explanation

The SRS describes what the system must do, not how it is built internally. It treats the system as a black box, so it is called a black-box specification.

Explanation

Reverse engineering analyses existing code to recover its design and requirements specification. It is often used when maintaining legacy software.

Explanation

The spiral model is called a meta model because it includes the other models: each loop can use waterfall, prototyping or incremental steps, with risk analysis added.

Explanation

In the brute force debugging method, the program is filled with print statements and memory dumps in the hope that the printed values will reveal the faulty statement. It is the most common but least efficient method.

Explanation

Java's relational operators are <, >, <=, >=, == and !=. "=>" is not a valid operator in Java.

Explanation

Linux is a classic monolithic kernel. The Windows NT kernel also runs most OS services in kernel mode and is usually described as hybrid, but the exam treats both as monolithic.

Explanation

Threads give concurrency inside a single process. A process gives protection: each process has its own address space and resources. Both statements are true.

Explanation

A thread belongs to its process and shares only that process's resources, so it is private to the process. Threads of one process are not visible to other processes, so statement I is false.

Explanation

The standard process states are new, ready, running, waiting (blocked) and terminated. "Excite" is not a process state.

Explanation

C-SCAN is a disk scheduling algorithm. FCFS, SJF and SJN (shortest job next) are CPU scheduling algorithms.

Explanation

SRTF keeps choosing short jobs, so long jobs can starve. Round Robin gives every process a time slice quickly, so its response time is better than FCFS. Both statements are true.

Explanation

Because of the law of variable proportions, short-run marginal cost first falls and then rises, so the SMC curve is U-shaped.

Explanation

Repo rate, reverse repo rate and bank rate are all quantitative instruments that the RBI uses to control money supply and credit.

Explanation

In monopolistic competition, products are differentiated, so each firm faces a downward-sloping demand curve. A horizontal demand curve belongs to perfect competition.

Explanation

A LAN covers a limited area and is faster than a WAN. Communication through satellites and microwave links is a feature of a WAN, so only II and III are true.

Explanation

A WAN covers a wide geographical area and often uses satellites and microwave links. It is slower than a LAN, not faster, so statement III is false.

Explanation

ICMP stands for Internet Control Message Protocol. It carries error and control messages for IP, and ping and traceroute use it.

Explanation

Statement I is true: if the central hub fails, the whole star network goes down. Statement II is false: each node has its own link to the hub, so adding computers does not noticeably increase communication time.

Explanation

Manchester encoding has a transition in the middle of every bit, so each bit becomes two half-bit pulses. The pulse width is half that of straight binary, which doubles the baud rate.

Explanation

Circuit switching sets up a dedicated path between sender and receiver for the whole session, as in a telephone call. Packet and message switching share links.

Explanation

In VB.NET, Append is used as a symbolic constant (OpenMode.Append) in the FileOpen function, to open a file and add data at its end.

Explanation

Transplanted real-world models are offline business models moved to the internet, such as mail-order, advertising, subscription and free trial. Freeware, access provision and digital products are native internet models.

Explanation

Online trading involves all three steps: open a demat and online trading account, move funds from the bank account to the trading account, and place the confirmed order on the stock exchange through the online system.

Explanation

An AVL tree allows each node a balance factor (left height minus right height) of only −1, 0 or +1. So 1 is valid, while 2, 3 and 4 would need a rebalancing rotation.

Explanation

A pendant vertex has degree exactly one. An isolated vertex has degree zero.

Explanation

The matrix is square, vertex by vertex, and entry (i, j) = 1 exactly when vi and vj are joined by an edge. For example, V1 is joined to V3 and V4. So it is the adjacency matrix. An incidence matrix would be vertex by edge.

Explanation

Path costs: V1→V2→V3→V5 = 130, V1→V4→V3→V5 = 120, V1→V4→V5 = 130 and V1→V5 = 120. The minimum is 120.

Explanation

A DSS has a user interface for interacting with the user, plus a database and a model base or knowledge engine that does the analysis. Both are components.

Explanation

CDMA was first used commercially in cdmaOne (IS-95), a 2G digital cellular standard. Later CDMA-based 3G systems were CDMA2000 and WCDMA.

Explanation

The data speeds rise in this order: GSM (about 9.6-14.4 kbps), GPRS (about 114 kbps), EDGE (about 384 kbps), then LTE (tens to hundreds of Mbps).

Explanation

A circle is symmetric in all eight octants, so computing one point (x, y) gives eight points (±x, ±y) and (±y, ±x). Bresenham's and the midpoint algorithms use this.

Explanation

The rotation matrix is [cosθ −sinθ; sinθ cosθ]. With cos30° = √3/2 and sin30° = 1/2, this gives [√3/2 −1/2; 1/2 √3/2].

Explanation

HSL stands for Hue, Saturation and Lightness, for example hsl(120, 100%, 50%). Hue is an angle from 0 to 360°, and saturation and lightness are percentages.

Explanation

JPEG stands for Joint Photographic Experts Group, the committee that created this lossy image compression standard.

Explanation

In a sequence structure, statements run one after another in the written order. Each runs exactly once and none repeats. They are not executed in any order, so III is false.

Explanation

Sorted, the data is 9,15,16,20,23,26,28,32,33,34,35,43, so P = (26+28)/2 = 27. After the replacements it is 9,15,20,26,28,30,32,32,33,34,35,43, so Q = (30+32)/2 = 31. Then 3P − 2Q = 81 − 62 = 19.

Explanation

By Bayes' theorem, P(M | red) = (½ × 5/9) / (½ × 3/5 + ½ × 5/9) = (5/9) / (52/45) = 25/52.

Explanation

With two points, Lagrange's formula gives f(x) = 3(x−4)/(2−4) + 5(x−2)/(4−2) = −1.5x + 6 + 2.5x − 5 = x + 1. Check: f(2) = 3 and f(4) = 5.

Explanation

Effective teaching lets students learn from peers and encourages them to think independently and build their own knowledge, as constructivism suggests. Both are characteristics.

Explanation

Activity materials should be relevant, contextual and linked to real life. The textbook is still an essential basic resource for teaching and learning. Both statements are accepted as correct.

Explanation

Formative assessment is continuous and built into everyday teaching. It is diagnostic and remedial, involves students and gives feedback. Holding it at fixed intervals is more typical of periodic or summative assessment.

Explanation

Statement I describes assessment of learning (summative), which measures achievement after teaching. Statement II describes assessment for learning (formative), which uses results during teaching to improve learning. Both are correct.

Explanation

Acquisition happens naturally through use in real communicative settings, like a home language. Learning happens through explicit classroom teaching of rules and vocabulary. Both definitions are correct.

Explanation

Art education covers both visual or tangible arts, such as drawing, painting and sculpture, and performing arts, such as music, dance and drama.

Explanation

Regional art and craft comes from the people of a region and reflects their traditional culture. It has its own folk aesthetics and is not bound by classical rules of proportion and rhythm. Both statements are taken as correct.

Explanation

To promote gender equality, teachers should use gender-neutral language and avoid giving tasks based on gender stereotypes. Both practices help.

Explanation

Gender discrimination can come from unequal educational opportunities, from government policies and from family and parents' attitudes, so all three are sources.