NBT Logical Reasoning & Problem Solving 2 — Questions and Answers
Question 1: All students in the maths class passed the exam. Thabo is a student in the maths class. What must be true?
- Thabo failed the exam
- Thabo may have passed the exam
- Thabo passed the exam (Correct answer)
- Thabo is not in the maths class
Correct answer: Thabo passed the exam
This is a valid deductive argument (syllogism). If all students passed and Thabo is a student in the class, then Thabo must have passed.
Question 2: A pattern of numbers: 3, 6, 12, 24, ___. What is the next number?
- 36
- 42
- 48 (Correct answer)
- 50
Correct answer: 48
Each term is multiplied by 2. 24 × 2 = 48.
Question 3: Siya is taller than Bongani. Bongani is taller than Lungile. Which of the following must be true?
- Lungile is taller than Siya
- Siya is taller than Lungile (Correct answer)
- Bongani is the shortest
- All three are the same height
Correct answer: Siya is taller than Lungile
If Siya > Bongani and Bongani > Lungile, then by transitivity: Siya > Lungile.
Question 4: If "all mammals breathe air" and "dolphins are mammals," what is the logical conclusion?
- All animals breathe air
- Some mammals do not breathe air
- Dolphins breathe air (Correct answer)
- Dolphins are not mammals
Correct answer: Dolphins breathe air
Valid deductive reasoning: dolphins are mammals (given), all mammals breathe air (given), therefore dolphins breathe air.
Question 5: A student must choose 2 subjects from: Mathematics, History, Science, and Art. How many different combinations are possible?
- 4
- 5
- 6 (Correct answer)
- 8
Correct answer: 6
Combinations: C(4,2) = 4! / (2! × 2!) = (4 × 3) / (2 × 1) = 6 combinations.
Question 6: A box contains 4 red, 3 blue, and 3 green balls. One ball is drawn at random. What is the probability of drawing a red ball?
- 1/4
- 2/5 (Correct answer)
- 3/10
- 4/10
Correct answer: 2/5
Total balls: 4 + 3 + 3 = 10. P(red) = 4/10 = 2/5.
NBT Logical Reasoning & Problem Solving 2
All students in the maths class passed the exam.
Thabo is a student in the maths class.
What must be true?