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S3 ICT: Algorithms and Flowcharts (Paper 2: intermediate)
S3 ICT: Algorithms and Flowcharts (Paper 2: intermediate)
S3 ICT algorithms and flowcharts paper two, intermediate: ten questions on choosing FOR or WHILE, decision exits, nested loop counts, conditional accumulation and binary search comparisons.
Direct answers Answers in order: count controlled against condition controlled, two exits, the left arrow, four times, twelve times, four rounds with x equal to -2, 12, about ten comparisons, 7, and WHILE tests before it runs.
01 Paper details (check answers afterwards)
| Item | Detail |
|---|---|
| Questions | 10 |
| Suggested time | 20 |
| Difficulty mix | Foundation 3 · Intermediate 3 · Challenge 3 · Error redo 1 |
| Chapter | Chapter: S3 ICT: Algorithms and Flowcharts |
| Level | S3 |
02 Questions (10 items)
- FoundationWhat is the main difference between a FOR loop and a WHILE loop?
- FoundationHow many exits does a decision symbol have?
- FoundationWhich symbol usually assigns a value to a variable in pseudocode?
- IntermediateHow many times does FOR i = 2 TO 8 STEP 2 run?
- IntermediateAn outer loop runs FOR i = 1 TO 3 and an inner loop runs FOR j = 1 TO 4. How many inner rounds in total?
- IntermediateWith x = 10 and WHILE x > 0 doing x = x – 3, how many rounds run and what is the final x?
- ChallengeWith sum = 0 and FOR i = 1 TO 6 adding i only when i MOD 2 = 0, what is the final sum?
- ChallengeAbout how many comparisons does binary search need on 1 000 sorted items?
- ChallengeWith x = 1, count = 0 and WHILE x < 100 doubling x and adding one to count each round, what is the final count?
- Error redoA student says a WHILE loop always runs at least once. What is wrong?
03 Answers and one-line notes
| # | Answer | One-line note |
|---|---|---|
| 1 | FOR is count controlled with a known number of rounds, while WHILE is condition controlled and may run an unknown number of times | Use FOR when the count is known and WHILE when the stopping depends on a condition. |
| 2 | Two, one for yes and one for no | A condition either holds or fails, so there are always two branches. |
| 3 | The left arrow | The arrow points from the expression on the right to the variable on the left, showing the direction of data flow. |
| 4 | Four times | The counter takes the values two, four, six and eight. |
| 5 | Twelve | Each outer round completes four inner rounds, so three times four is twelve. |
| 6 | Four rounds and the final x is -2 | The value falls to 7, 4, 1 and then -2, where the condition finally fails. |
| 7 | 12 | Only two, four and six are added, giving twelve. |
| 8 | About ten | Each step halves the range and two to the tenth power exceeds a thousand. |
| 9 | 7 | The value runs through 2, 4, 8, 16, 32, 64 and 128, so seven rounds run before the condition fails. |
| 10 | WHILE tests first, so a false condition at the start means zero rounds | The test comes before the body, so nothing runs when the condition fails immediately. |
04 What to do after marking
- After marking, redo only the wrong items and write down which step went wrong (formula, unit, or misread number).
- Repeat the same item two days later; move to the next paper only when both attempts are correct.
- Parents only need the answer and note columns; there is no need to explain every item.
An algorithm is a finite and unambiguous list of steps; flowcharts use a diamond for decisions and a parallelogram for input or output, combined through sequence, selection and iteration.Tutor Registration →
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