Which of the following measures the spread or dispersion of a random variable's values around its expected value?
Variance
Probability Mass Function
Expected Value
Cumulative Distribution Function
A random variable X has a probability distribution as follows: P(X=0) = 0.2, P(X=1) = 0.3, P(X=2) = 0.5. What is the expected value of X?
1.5
1.2
0.5
1
A committee of 3 people is to be formed from a group of 5. How many different committees are possible?
10
15
20
60
Which of the following is an example of a discrete random variable?
The weight of an apple.
The temperature of a room.
The height of a student.
The number of heads when a coin is flipped four times.
Which of the following is NOT a valid probability value?
0
0.75
1.25
What is the variance of a standard normal distribution (mean = 0, standard deviation = 1)?
2
You are playing a game where you roll a die until you get a 6. What is the probability that you will roll the die exactly 4 times before winning?
(1/6)^4
(1/6)^3 * (5/6)
(5/6)^3 * (1/6)
(5/6)^4 * (1/6)
If the PDF of a continuous variable is a flat line over a range, what does this imply about the distribution?
It's exponentially distributed.
It's normally distributed.
It's a Poisson distribution.
It's uniformly distributed.
You roll a fair six-sided die. What is the probability of rolling a number greater than 4?
1/2
1/6
2/3
1/3
A random variable representing the number of website visitors in an hour is an example of what type of variable?
Qualitative
Discrete
Ordinal
Continuous