NBT Statistics and Probability 1 — Questions and Answers
Question 1: What is the mean of the following data set: 12, 15, 18, 22, 28?
- 18
- 19 (Correct answer)
- 20
- 18.5
Correct answer: 19
The mean is the sum divided by the count: (12 + 15 + 18 + 22 + 28) ÷ 5 = 95 ÷ 5 = 19. The mean represents the average value.
Question 2: A fair die is rolled once. What is the probability of getting a number greater than 4?
- 1/6
- 1/3 (Correct answer)
- 1/2
- 2/3
Correct answer: 1/3
Numbers greater than 4 on a die are 5 and 6 — that's 2 favourable outcomes out of 6 possible. P = 2/6 = 1/3.
Question 3: What is the median of: 3, 7, 9, 12, 15, 18, 21?
- 9
- 12 (Correct answer)
- 15
- 13.5
Correct answer: 12
With 7 values in order, the median is the 4th value (middle). The median is 12. For an odd number of data points, the median is the exact middle value.
Question 4: If P(A) = 0.4 and P(B) = 0.3, and A and B are independent events, what is P(A and B)?
- 0.7
- 0.12 (Correct answer)
- 0.1
- 0.70
Correct answer: 0.12
For independent events, P(A and B) = P(A) × P(B) = 0.4 × 0.3 = 0.12. Independence means one event does not affect the probability of the other.
Question 5: The mode of a data set is:
- The middle value
- The average value
- The most frequently occurring value (Correct answer)
- The range of values
Correct answer: The most frequently occurring value
The mode is the value that appears most frequently in a data set. A data set can have no mode, one mode (unimodal), or multiple modes (bimodal or multimodal).
Question 6: In a class of 30 learners, 18 play soccer and 12 play cricket. If 6 play both sports, how many play neither?
- 0
- 4
- 6 (Correct answer)
- 8
Correct answer: 6
Using inclusion-exclusion: those playing at least one sport = 18 + 12 - 6 = 24. Those playing neither = 30 - 24 = 6.
NBT Statistics and Probability 1
What is the mean of the following data set: 12, 15, 18, 22, 28?