DSST Statistics 2 — Questions and Answers
Question 1: A dataset has a mean of 50 and a standard deviation of 5. What is the z-score for a value of 60?
- 1.0
- 2.0 (Correct answer)
- 0.5
- 1.5
Correct answer: 2.0
z = (60 - 50) / 5 = 2.0.
Question 2: Which measure of central tendency is most affected by extreme outliers?
- Median
- Mode
- Mean (Correct answer)
- Midrange
Correct answer: Mean
The mean is pulled toward extreme values because it uses all data points arithmetically.
Question 3: In a hypothesis test, a Type II error occurs when you:
- Reject a true null hypothesis
- Fail to reject a false null hypothesis (Correct answer)
- Correctly reject the null hypothesis
- Set alpha too high
Correct answer: Fail to reject a false null hypothesis
A Type II error (beta) is failing to detect a real effect — accepting a false null hypothesis.
Question 4: Which of the following correlation coefficients indicates the strongest linear relationship?
- r = 0.45
- r = -0.82 (Correct answer)
- r = 0.60
- r = -0.30
Correct answer: r = -0.82
The strength of a correlation depends on the absolute value; |-0.82| = 0.82 is the largest here.
Question 5: A probability distribution in which every outcome is equally likely is called a:
- Normal distribution
- Binomial distribution
- Uniform distribution (Correct answer)
- Poisson distribution
Correct answer: Uniform distribution
A uniform distribution assigns equal probability to all outcomes.
Question 6: The interquartile range (IQR) is calculated as:
- Q3 - Q1 (Correct answer)
- Q2 - Q1
- Q4 - Q1
- Max - Min
Correct answer: Q3 - Q1
IQR = Q3 - Q1, representing the spread of the middle 50% of data.
Question 7: If P(A) = 0.4 and P(B) = 0.3 and A and B are independent, what is P(A and B)?
- 0.70
- 0.12 (Correct answer)
- 0.10
- 0.58
Correct answer: 0.12
For independent events, P(A and B) = P(A) × P(B) = 0.4 × 0.3 = 0.12.
DSST Statistics 2
A dataset has a mean of 50 and a standard deviation of 5.
What is the z-score for a value of 60?