AP Statistics · Topic 4.7
Introduction to Random Variables and Probability Distributions Practice
Part of Probability, Random Variables, and Probability Distributions.(VAR-5.A)
Practice questions
10
Sample questions
5 of 10 — sign in to practice the rest with adaptive difficulty and mastery tracking.
Sample 1difficulty 2/5
A discrete RV takes values
- Acheck_circle
From a countable set
- B
From the empty set
- C
Only 0 or 1
- D
From a continuous interval
Why
Countable values; continuous RVs take any value in an interval.
- A
Sample 2difficulty 2/5
A Bernoulli RV (0/1) with success prob p has
- Acheck_circle
Mean p, Var p(1−p)
- B
Mean 1/p
- C
Mean = 0.5
- D
Mean 0, Var 1
Why
Mean p, Var p(1−p).
- A
Sample 3difficulty 2/5
X takes values 1, 2, 3 with P(1) = 0.1, P(2) = 0.3, P(3) = k.
What is k?
- Acheck_circle
0.6
- B
0.4
- C
0.5
- D
1.0
Why
Probabilities sum to 1. So k = 1 - 0.1 - 0.3 = 0.6.
- A
Sample 4difficulty 2/5
The probabilities in a PMF must sum to
- A
0.5
- B
0
- Ccheck_circle
1
- D
n
Why
Total probability across all outcomes = 1.
- A
Sample 5difficulty 2/5
A random variable is
- A
An event
- Bcheck_circle
A measurable function of the outcome of a chance process
- C
A constant
- D
Always discrete
Why
RV maps outcomes to numbers; discrete or continuous.
- A