Computer Science Previous Year Questions (page 7)

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24 = 0000 0000 0001 1000. Invert the bits (1111 1111 1110 0111) and add 1 to get 1111 1111 1110 1000, which is −24 in 2's complement.

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A skewed (degenerate) BST is like a linked list, so a search may have to visit all n nodes: O(n) in the worst case.

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In Boolean algebra, + is OR and · is AND. (0+0+0) = 0, so 0 · (0+1+1) = 0. Every other option has both factors equal to 1.

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With LRU and 4 frames: 7, 0, 1, 2 are 4 faults; 3 replaces 7; 4 replaces 1; then 1 replaces 4. All other references are hits, so there are 7 page faults.

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ReDim resizes a dynamic array in VB (ReDim Preserve also keeps its existing contents). Dim only declares the array.

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A consumer first does wait(F) to make sure a full slot exists, then wait(M) for mutual exclusion on the buffer, and only then removes the item.

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Clustered systems join several computers to provide high availability and high-performance computing. In asymmetric multiprocessing the processors are not peers, and multiprocessor does not always mean multicore.

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Each character takes 1 start + 7 data + 1 parity + 1 stop = 10 bits, so 2400 / 10 = 240 characters per second.

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The relational, hierarchical and network models are record-based logical models. The E-R model is an object-based conceptual model.

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Shared (read) locks are compatible with each other, so B's shared-lock request on R is granted immediately.

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A data model is a collection of conceptual tools for describing data, data relationships, data semantics and consistency constraints (Korth).

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Corrected: the book's key says (b). Set difference is neither commutative (R − S ≠ S − R) nor associative.

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The number of equivalence relations on a 4-element set equals the number of its partitions, which is the Bell number B₄ = 15.

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The range is the set of second elements (outputs) of the ordered pairs: {8, 2, −4}.

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Removing B separates {A, D} from {C, E}, and removing C cuts off E. Removing A, D or E leaves the graph connected, so the cut vertices are B and C.

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Spyware secretly monitors a user's activity, such as browsing and keystrokes, and sends that information to a third party in the background. Adware mainly shows unwanted advertisements.

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A*(B+C)/D is evaluated as (A*(B+C))/D. In prefix form this is / * A + B C D.

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In a B-tree of order p, every non-root node has at least ⌈p/2⌉ children. So the maximum height is log base ⌈p/2⌉ of (n+1)/2.

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8 2 3 ^ gives 2³ = 8, then 8 / 8 = 1. Next 2 and 3 are pushed and * gives 6. The stack now holds 1, 6, so the top two elements are 6 and 1.

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37→2, 38→3, 72→2 (taken, goes to 3, then 4), 48→6, 98→0. 11 mod 7 = 4 is taken, so linear probing places 11 at slot 5.

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In optical fibre, light stays inside the glass core by total internal reflection at the core-cladding boundary.

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Demand paging loads a page into memory only when it is referenced, which triggers a page fault.

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This is the subtraction form of Euclid's algorithm: repeatedly subtracting the smaller number from the larger one until both are equal leaves their GCD.

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(A+C)(AB'+AC) = AB' + AC by absorption. Multiplying by (A' + B' + C') gives AB' + AB'C = AB'.

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MOV is a data transfer instruction. JMP and CALL change the flow of control, and CMP is used with jumps to make decisions, so these are program control instructions.

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Emitter-Coupled Logic (ECL) is the fastest logic family, because its transistors never saturate, but it uses a lot of power.

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Each recursive call pushes its return address and local variables onto a stack, so recursion is implemented with a stack.

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Inserting B, I, N, A, R, Y gives root B with A on the left and the chain I → N → R → Y to the right. The longest path B-I-N-R-Y has 4 edges, so the height is 4.

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confirm() shows a dialog with a message and OK and Cancel buttons and returns true or false. alert() has only OK, and prompt() also asks for text input.

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The XML declaration is a processing instruction: <?xml version="1.0"?>. It begins with <?xml and the version value is quoted. Option B is the closest to this form.

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and is a logical operator in Python (as are or and not). in is a membership operator, <= is relational and += is assignment.

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Python identifiers cannot start with a digit or contain spaces, so "1st Name" is invalid.

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A parameter without a default value cannot follow parameters that have default values. def Compu(X=100, Y=10, Z): raises a SyntaxError.

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The csv writer object's writerow() method writes one row (line) to a CSV file. writerows() writes several rows.

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A=100: S=100, A=60. A=60: S=160, A=20. A=20 (still ≥ 20): S=180, A=−20. The condition is now false, so the output is 180.

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pl.plot([5, 2, 3, 1]) draws a line graph, using the indexes 0-3 as x values. bar and scatter give different charts, and pl.line does not exist.

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The degree of a relation is its number of attributes (columns). Cardinality is the number of tuples (rows).

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Observing keenly, making notes and sharing observations encourages active, inquiry-based and collaborative learning.

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Learning by doing (planting seeds and watching them germinate) gives direct experience, which is the most effective way to teach this concept.

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onmouseover fires when the pointer enters the link, and onmouseout fires when it leaves. There are no OnMouseIn or OnMouseExit events.

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open(), close() and prompt() are methods of the window object. name is a property (window.name), not a method.

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The new node's next and prev pointers are set, and the next pointer of the previous node and the prev pointer of the following node are updated. That makes 4 pointer changes.

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The loop must stop at the end of the list or when X is found, so it continues only while P != NULL && P→Element != X. Checking for NULL first also avoids dereferencing a null pointer.

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The NOR gates give (A+B)' and (C+D)', and the AND gate combines them, so the output is (A+B)' · (C+D)'.

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By the absorption law, a + a·b = a(1 + b) = a·1 = a.

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Optical fibre gives high bandwidth over long distances with little loss and no electromagnetic interference, so it is best for linking offices in different cities.

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GSM stands for Global System for Mobile Communication, the 2G digital cellular standard.

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A Trial Balance lists all ledger balances to check that total debits equal total credits, which tests the arithmetical accuracy of the ledger accounts.

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The Sales Book (Sales Journal) records only credit sales of goods. Cash sales go to the Cash Book.

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Fitting a new experience (another dog) into an existing schema is assimilation in Piaget's theory. Accommodation means changing the schema itself.