Time allowed: 45 minutes
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Candidate number |
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| First name |
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Last name |
INSTRUCTIONS
- Use black ink.
- Answer all the questions.
INFORMATION
- The total mark for this paper is 26.
- The marks for each question are shown in brackets [ ].
Turn over
Section A: Mathematical Notation
1
The following truth table represents the expression:
Q = ¬A ∨ B
Complete the truth table.
[4]
| A |
B |
¬A (NOT A) |
Q |
| 0 | 0 | | |
| 0 | 1 | | |
| 1 | 0 | | |
| 1 | 1 | | |
2
Match the mathematical expression to the correct English description.
Draw a line (or write the letter pair) to connect them.
[3]
| Expression |
|
Description |
| A. A ∧ B |
|
1. A OR B |
| B. ¬A |
|
2. A AND B |
| C. A ∨ B |
|
3. NOT A |
Section B: The "Killer" 3-Input Table
3
Complete the truth table for the logic expression:
P = (A AND B) OR C
Tip: Calculate the bracket (A AND B) first.
[5]
| A | B | C | (A AND B) | P |
| 0 | 0 | 0 | | |
| 0 | 0 | 1 | | |
| 0 | 1 | 0 | | |
| 0 | 1 | 1 | | |
| 1 | 0 | 0 | | |
| 1 | 0 | 1 | | |
| 1 | 1 | 0 | | |
| 1 | 1 | 1 | | |
Turn over
Section C: Debugging & Error Identification
4
A student has attempted to complete a truth table for the expression
P = NOT (A OR B).
Their answer is shown below. They have made two mistakes.
Student's Incorrect Work:
| A | B | A OR B | P |
|---|
| 0 | 0 | 0 | 1 |
| 0 | 1 | 1 | 0 |
| 1 | 0 | 0 | 1 |
| 1 | 1 | 1 | 0 |
(i) Identify the Row number where the first error occurs in the calculation.
[1]
(ii) Explain why the value in the final column (P) for Row 3 is considered incorrect based on the student's working, even if the math seems right for that step.
[1]
(iii) State the correct Final Output for Row 3.
[1]
Section D: Reverse Engineering
5
A security light system has two inputs:
M: Motion Detected (1 = Motion, 0 = No Motion)
N: Night Time (1 = Night, 0 = Day)
The system is designed so the light turns ON (1) only when Motion is detected
AND it is Night time.
(i) Look at the Truth Table below. Does this table correctly represent the system described above?
Write YES or NO.
[1]
(ii) Justify your answer.
[2]
Section E: Circuit Logic Tracing
6
Consider a logic circuit configured as follows:
- Input A and Input B go into an OR gate.
- The output of that OR gate goes into an AND gate.
- Input C goes into the other connection of that AND gate.
Complete the final two rows of the truth table for this circuit.
[4]
| A | B | C | A OR B | Final Output |
|---|
| ... | ... | ... | ... | ... |
| 1 | 1 | 0 | | |
| 1 | 1 | 1 | | |
END OF QUESTION PAPER