College Math Placement Test Statistics 2 — Questions and Answers
Question 1: A dataset has values 4, 8, 6, 5, 3, 2, 8, 9, 8, 1. What is the mode?
- 6
- 5.4
- 8 (Correct answer)
- 5.5
Correct answer: 8
The mode is 8 because it appears 3 times, more than any other value.
Question 2: Which measure of central tendency is most affected by extreme outliers?
- Median
- Mode
- Mean (Correct answer)
- Range
Correct answer: Mean
The mean is most affected by outliers because it uses every value in its calculation.
Question 3: A sample of 5 test scores has a variance of 36. What is the standard deviation?
- 6 (Correct answer)
- 18
- 1296
- 7.2
Correct answer: 6
Standard deviation is the square root of variance, so √36 = 6.
Question 4: In a normal distribution, approximately what percentage of data falls within one standard deviation of the mean?
- 50%
- 68% (Correct answer)
- 95%
- 99.7%
Correct answer: 68%
The empirical rule states that about 68% of data falls within one standard deviation of the mean.
Question 5: A bag contains 4 red, 3 blue, and 5 green marbles. What is the probability of drawing a blue marble?
- 1/4
- 3/12 (Correct answer)
- 1/3
- 1/5
Correct answer: 3/12
There are 3 blue out of 12 total marbles, so P(blue) = 3/12 = 1/4.
Question 6: If two events A and B are mutually exclusive, which statement 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 both occur simultaneously, so their joint probability is 0.
Question 7: A frequency table shows Class 1: 10 students, Class 2: 15 students, Class 3: 5 students. What is the relative frequency of Class 2?
- 15%
- 0.5 (Correct answer)
- 50%
- 15/30
Correct answer: 0.5
Relative frequency = 15/30 = 0.5, meaning Class 2 represents half of all students.
College Math Placement Test Statistics 2
A dataset has values 4, 8, 6, 5, 3, 2, 8, 9, 8, 1.
What is the mode?