Probability Distributions Questions with Solutions

11 questions5 easy6 medium

A random variable assigns a number to each outcome of a random experiment, and its probability distribution lists the probability of each value. This topic covers discrete random variables and their probability mass functions, continuous random variables and their probability density functions, and the cumulative distribution function. It also covers the expected value (mean) E(X) = sum of x p(x), the variance Var(X) = E(X^2) - [E(X)]^2, and the standard deviation. A common question type gives a probability distribution with an unknown constant k. Since all probabilities must add up to 1 (or the density must integrate to 1), you can find k first and then answer the rest of the question. Questions also ask you to build the distribution from a situation, such as the number of heads when three coins are tossed. Practise the probability distribution questions below, each with a step-by-step solution.

  1. Q1.

    The probability distribution function of a random variable is given by Then the value of is

    A. B. C. D.
    mediumAsked in MAH MCA CET 2025View solution ›
  2. Q2.

    If, for a binomial distribution, the number of trials is , the variance is and the probability of success is greater than that of failure, find the probability of both success.

    A. B. C. D.
    mediumAsked in MAH MCA CET 2025View solution ›
  3. Q3.

    A random variable X has the following Probability Mass Function: : 0, 1, 2 : , , Then the variance of X is

    A. B. C. D.
    mediumAsked in MAH MCA CET 2024View solution ›
  4. Q4.

    In a Poisson distribution, if , then , where equals

    A. B. C. D.
    mediumAsked in NIMCET 2010View solution ›
  5. Q5.

    The scores of students in a national level examination are normally distributed with a mean of 500 and a standard deviation of 100. If the value of the cumulative distribution of the standard normal random variable at 0.5 is 0.691, then the probability that a randomly selected student scored between 450 and 500 is

    A. 0.091B. 0.591C. 0.391D. 0.191
    mediumAsked in NIMCET 2025View solution ›
  6. Q6.

    The number of accidents per week in a town follows a Poisson distribution with mean 3. If the probability that there are three accidents in two weeks' time is , then the value of is

    A. 9B. 27C. 36D. 18
    mediumAsked in NIMCET 2025View solution ›