NBT NBT Statistics and Probability 4 — Questions and Answers
Question 1: A dataset has values 5, 8, 8, 10, 12, 15, 15, 15, 20. What is the mode?
- 8
- 10
- 15 (Correct answer)
- 12
Correct answer: 15
The mode is 15 because it appears three times, more than any other value.
Question 2: If two events A and B are mutually exclusive, which of the following is true?
- P(A and B) = P(A) × P(B)
- P(A and B) = 0 (Correct answer)
- P(A or B) = P(A) × P(B)
- P(A and B) = P(A) + P(B)
Correct answer: P(A and B) = 0
Mutually exclusive events cannot occur simultaneously, so P(A and B) = 0.
Question 3: A box contains 4 red, 3 blue, and 5 green marbles. What is the probability of NOT picking a blue marble?
- 3/12
- 9/12 (Correct answer)
- 7/12
- 5/12
Correct answer: 9/12
P(not blue) = (4+5)/12 = 9/12 = 3/4.
Question 4: The interquartile range (IQR) of a dataset is best described as:
- The difference between the maximum and minimum values
- The middle value of the dataset
- The difference between the third and first quartiles (Correct answer)
- The average of all values
Correct answer: The difference between the third and first quartiles
The IQR = Q3 − Q1, representing the spread of the middle 50% of the data.
Question 5: A student scores 72, 85, 90, 68, and 75 on five tests. What is the mean score?
- 76
- 78 (Correct answer)
- 80
- 74
Correct answer: 78
Mean = (72+85+90+68+75)/5 = 390/5 = 78.
Question 6: Which measure of central tendency is most affected by extreme outliers?
- Median
- Mode
- Mean (Correct answer)
- Range
Correct answer: Mean
The mean is most sensitive to outliers because it uses all values in its calculation.
Question 7: A fair coin is flipped three times. What is the probability of getting exactly two heads?
- 1/8
- 3/8 (Correct answer)
- 1/4
- 1/2
Correct answer: 3/8
There are 3 favorable outcomes (HHT, HTH, THH) out of 8 total, so P = 3/8.
NBT NBT Statistics and Probability 4
A dataset has values 5, 8, 8, 10, 12, 15, 15, 15, 20.
What is the mode?