Probability distributions - binomial, Poisson, normal, gamma, beta, Cauchy, multinomial, hypergeometric, negative binomial - One Line Questions
1.
The median of a standard Normal distribution (mu=0, sigma=1) is: —
0
2.
In a binomial experiment, if n=10 and p=0.5, what is the probability of getting exactly 5 successes? —
0.246
3.
In the context of the Beta distribution, if alpha = 1 and beta = 1, what distribution does it represent? —
A uniform distribution on [0, 1]
4.
The Gamma distribution is a generalization of the exponential distribution. If the shape parameter k=1, the Gamma distribution becomes: —
An Exponential distribution
5.
The Multinomial distribution is a generalization of the binomial distribution. It describes the outcome of: —
A fixed number of independent trials, each with more than two possible outcomes
6.
A single draw from a Multinomial distribution with parameters n and p1, p2, ..., pk results in: —
A vector of k counts, summing to n, representing the number of times each outcome occurred.
7.
Consider a sequence of Bernoulli trials. The Negative Binomial distribution models the probability of obtaining: —
A specific number of failures before the k-th success.
8.
Which distribution is characterized by the probability of k successes in n trials, where sampling is done WITHOUT replacement from a finite population of size N containing K successes? —
Hypergeometric
9.
When sampling from a finite population without replacement, if we are interested in the number of successes in a fixed number of draws, which distribution is appropriate? —
Hypergeometric distribution
10.
If a die is rolled 10 times, and we are interested in the number of times each face (1 through 6) appears, which distribution would model this scenario? —
Multinomial distribution
11.
A box contains 10 red balls and 5 blue balls. If 3 balls are drawn without replacement, the probability distribution for the number of red balls drawn follows: —
Hypergeometric distribution
12.
The Beta distribution is related to the Gamma distribution through the Beta function B(x, y) = Gamma(x)Gamma(y) / Gamma(x+y). This relationship is useful for: —
Both A and B.
13.
The Cauchy distribution's heavy tails mean that: —
Extreme values are more likely than in a normal distribution.
14.
Which continuous probability distribution is bell-shaped, symmetric, and characterized by its mean (mu) and standard deviation (sigma)? —
Normal distribution
15.
Which distribution is characterized by the probability density function f(x) = (1 / (sigma * sqrt(2*pi))) * exp(-0.5 * ((x - mu) / sigma)^2)? —
Normal distribution
16.
The Cauchy distribution has a characteristic function (phi(t)) given by exp(|t|). This implies: —
It has heavy tails.
17.
Which of the following is a property of the Normal distribution? —
It is symmetric about its mean.
18.
The variance of a Poisson distribution with parameter lambda is: —
lambda
19.
The Cauchy distribution is known for its heavy tails and lack of a well-defined mean or variance. What is its characteristic parameter? —
Mu (location) and Sigma (scale)
20.
The probability density function of a Poisson distribution with parameter lambda is given by P(X=k) = (lambda^k * e^(-lambda)) / k! for k = 0, 1, 2, ... . This formula is valid when: —
lambda > 0.
21.
If X follows a Poisson distribution with parameter lambda, what is the expected value (mean) of X? —
lambda
22.
What are the parameters of a Beta distribution, typically denoted by alpha and beta? —
Two positive shape parameters
23.
In a standard normal distribution, what are the values of the mean and standard deviation? —
Mean = 0, Standard Deviation = 1
24.
What are the parameters of a Gamma distribution, typically denoted by k (shape) and theta (scale)? —
Shape and Scale
25.
The probability density function of the Cauchy distribution is f(x; x0, gamma) = 1 / (pi * gamma * [1 + ((x - x0)/gamma)^2]). Here, x0 and gamma represent: —
Location and Scale
26.
The Poisson distribution is often used to model the number of events occurring in a fixed interval of time or space, provided these events occur with a known average rate and independently of the time since the last event. What parameter characterizes the Poisson distribution? —
lambda (average rate of occurrence)
27.
Which parameters define a Hypergeometric distribution? —
N (population size), K (number of success states in population), and n (number of draws)
28.
The Gamma function, denoted by Gamma(z), is fundamental to the Gamma distribution. What is Gamma(n) for a positive integer n? —
(n-1)!
29.
When the number of trials 'n' in a binomial distribution becomes very large and the probability of success 'p' becomes very small, such that np = lambda (a constant), the binomial distribution can be approximated by which other distribution? —
Poisson distribution
30.
Which distribution is characterized by the fact that the sum of two independent Gamma random variables with parameters (k1, theta) and (k2, theta) is a Gamma random variable with parameter (k1+k2, theta)? —
Gamma distribution
31.
The sum of 'n' independent and identically distributed standard normal random variables follows a: —
Chi-squared distribution with n degrees of freedom
32.
For a binomial distribution B(n, p), what is the variance? —
np(1-p)
33.
The Normal distribution can be used to approximate the Binomial distribution when 'n' is large and 'p' is not too close to 0 or 1. What condition is typically used to determine if the approximation is valid? —
np > 5 and n(1-p) > 5
34.
Which probability distribution is characterized by a fixed number of independent trials, each with two possible outcomes (success or failure), and a constant probability of success? —
Binomial distribution
35.
The limiting distribution of the sum of a large number of independent and identically distributed random variables (under certain conditions) is the: —
Normal distribution
36.
What is a common parameterization for the Negative Binomial distribution, often denoted by r and p? —
r = number of successes, p = probability of success
37.
Which of the following statements about the Normal distribution is FALSE? —
The total area under the curve is infinite.
38.
The Cauchy distribution is sometimes called the 'Lorentz distribution'. A key characteristic is that its mean is undefined because: —
The integral of x*f(x) from -infinity to +infinity does not converge.
39.
In a multinomial distribution with k possible outcomes, what do the parameters typically represent? —
The number of trials and the probability of each outcome
40.
The Negative Binomial distribution parameter 'r' typically represents: —
The target number of successes.
41.
The Gamma distribution is a continuous probability distribution often used to model: —
The waiting time until a certain number of events occur
42.
The Negative Binomial distribution describes the probability of: —
The number of failures before the r-th success
43.
The Negative Binomial distribution can be viewed as the distribution of the number of trials needed to achieve a fixed number of successes. What is the alternative definition? —
The number of failures before the r-th success.
44.
A common application of the Beta distribution is in Bayesian statistics for modeling: —
The posterior distribution of a probability parameter.
45.
In a binomial distribution B(n, p), what does 'n' represent? —
The total number of independent trials
46.
The sum of independent Gamma random variables with the same scale parameter is also a Gamma random variable. What is the shape parameter of the resulting distribution? —
The sum of the original shape parameters.
47.
The Beta distribution is often used to model probabilities or proportions, which are bounded between 0 and 1. If alpha > 1 and beta > 1, the Beta distribution will be: —
Unimodal and concentrated around the mean
48.
The Beta distribution is a continuous probability distribution defined on the interval [0, 1]. It is often used to model: —
Proportions or percentages
49.
The variance of a Binomial distribution B(n, p) is always less than or equal to its mean (np). When is the variance equal to the mean? —
When p = 0
50.
The Hypergeometric distribution is used when sampling is done: —
Without replacement