DSE Information And Communication Technology Practice Paper (12 Questions, 50 Marks, 75 Minutes)

DSE Information and Communication Technology Practice Paper (12 Questions, 50 Marks, 75 Minutes)

2026-11-02

DSE ICT Full Practice Paper

DSE ICT paper: 12 questions, 50 marks, 75 minutes on data size, bandwidth, subnets, pseudocode, databases and encryption, with full worked solutions.

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Paper details　Level: S6 | Subject: Information and Communication Technology | Time: 75 minutes | Marks: 50 | Questions: 12

Section A (Q1-Q6, 2 marks each, 12 marks)

Write the formula, substitute the numbers and give the units (MiB, seconds, hours, addresses, records).

#	Question	Answer and marking notes
1	A 1920 × 1080 pixel 24-bit colour image uses 3 bytes per pixel. What is its uncompressed file size in MiB? (1 MiB = 1,048,576 bytes; give 2 decimal places)	Bytes = 1920 × 1080 × 3 = 6,220,800; MiB = 6,220,800 ÷ 1,048,576 ≈ 5.93 MiB.
2	An uncompressed WAV file is recorded in stereo at 44.1 kHz with 16-bit sampling for 3 minutes. What is its size in MiB? (2 decimal places)	Bytes = 44,100 × 2 (stereo) × 2 (bytes) × 180 s = 31,752,000; MiB = 31,752,000 ÷ 1,048,576 ≈ 30.28 MiB.
3	A 12 MB file is sent over a download bandwidth of 8 Mbps. Ignoring overhead, what is the minimum time in seconds? (1 MB = 8 Mb)	File size = 12 × 8 = 96 Mb; time = 96 ÷ 8 = 12 seconds.
4	The network 192.168.10.0/24 uses the subnet mask 255.255.255.0. How many usable host addresses can this subnet provide?	Host bits = 32 − 24 = 8; usable addresses = 2^8 − 2 = 254 (network and broadcast addresses removed).
5	A program runs on a computer: total = 0; for i in range(1, 11): total = total + i. What is total after the loop, and how many times does the loop run?	total = 1 + 2 + … + 10 = 55; the loop runs 10 times (i from 1 to 10).
6	The score column of a marks table holds six records: 72, 58, 64, 49, 88, 60. What does SELECT COUNT(*) FROM marks WHERE score >= 60 return?	The records meeting the condition are 72, 64, 88 and 60, so the count is 4.

Section B (Q7-Q9, 4 marks each, 12 marks)

Show every step; an answer without working earns at most half the marks.

#	Question	Answer and marking notes
7	Trace the pseudocode below. State the final values of n and count, and list the sequence of values taken by n: n = 27 count = 0 while n > 1: if n % 3 == 0: n = n // 3 else: n = n – 1 count = count + 1	Sequence: 27 → 9 (÷3) → 3 (÷3) → 1 (÷3); finally n = 1 and count = 3.
8	Compare the key properties of symmetric and asymmetric encryption, and explain why HTTPS uses both when a connection is established.	Symmetric encryption uses one shared key: fast, but key distribution is hard. Asymmetric encryption encrypts with a public key and decrypts with a private key, which solves key distribution but is slower. HTTPS first uses asymmetric encryption (certificate and public key) to exchange a temporary symmetric session key, then transfers data with fast symmetric encryption, so it gains both security and speed.
9	A student table has 1200 records of about 480 bytes each. Without an index a query reads all 1200 pages; with an index it reads only 12 pages. Find the size of the table in KiB and the percentage reduction in page reads, and state what normalisation does for such a table.	Table size = 1,200 × 480 = 576,000 bytes = 562.5 KiB; reduction = (1,200 − 12) ÷ 1,200 × 100% = 99.00%. Normalisation splits repeated data into separate tables, cutting redundancy and update anomalies and keeping indexes smaller and faster.

Section C (Q10-Q12, 26 marks)

Calculate or describe first, then explain in full sentences, referring to the figures given.

#	Question	Answer and marking notes
10	A library lending system handles the “student borrows a book” process. (a) Describe the flow, including its decisions. (b) Name two entities and their relationship. (c) Write one input validation rule and state how a violation is handled.	(a) Student enters the ID, the system validates the account, then checks outstanding fines: if any, refuse and notify; otherwise check availability: if unavailable, offer a reservation; if available, record the loan and due date and update the item status. (b) Entities: Student and Book; relationship: one student borrows many books, and one copy is lent to one student at a time. (c) Validation rule: the student ID must be 8 digits and must exist in the student table; on failure the transaction is rejected, an error message is shown and the item status stays unchanged.
11	The weekly online hours of eight students are 12, 18, 9, 21, 15, 15, 27 and 7. Find the mean, median and mode, and the standard deviation using the population formula (2 decimal places). Which measure of central tendency is least affected by an extreme value?	Mean = 124 ÷ 8 = 15.5 hours; sorted values are 7, 9, 12, 15, 15, 18, 21, 27, so the median = (15 + 15) ÷ 2 = 15; mode = 15; population standard deviation = 6.08 hours. The median is least affected by an extreme value.
12	A usage report shows one user spent 300 minutes on a social media app over five days. Find the daily average, then state two risks of excessive social media use and two practical suggestions for improvement.	Daily average = 300 ÷ 5 = 60 minutes (about 7 hours per week). Risks: reduced sleep and concentration; anxiety or cyberbullying caused by constant comparison. Suggestions: set a daily limit and turn off push notifications; keep the hour before sleep offline and replace scrolling with exercise or face-to-face contact.

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