Statistics

posted by .

You have a ten question multiple choice test in your next class and you did not study at all. Each question has four choices and only one correct answer. You are going to guess on each question. What is the probability that you score at least a 20% on the test.

  • Statistics -

    Use binomial probability because:
    probability is known and does not change over the experiment,
    outcome is binomial (success or failure),
    each step of the experiment is similar,

    p=0.25
    n=10
    P(r)=number of question correct
    =nCr(p^r)(1-p)^(n-r)

    nCr = binomial coefficient = n!/((n-r)!r!)

    P(0)=0.0563 (zero question correct)
    P(1)=0.1877 (1 question correct)

    Therefore, to get at least 20%, or 2 or more questions correct, we have
    P(2+)=1-(P(0)+P(1))
    =0.7560

Respond to this Question

First Name
School Subject
Your Answer

Similar Questions

  1. Math

    Given a multiple choice test with 4 choices for each question and 17 questions, What are the odds of getting all 17 questions incorrect?
  2. English for john browm

    Let me give you something on "multiple-choice" items that may help you to guess better. Many teachers prepare multiple-choice tests because they are easy to mark and offer the student the advantage of actually seeing what the correct …
  3. Statistics

    On a very short quiz, there is one multiple choice question with 5 possible choices (a, b, c, d, e) and one true or false question. Assume you are taking the quiz but do not have any idea what the correct answer is to either question. …
  4. stats

    You took a 5-question multiple choice quiz with 4 choices for each question. If you guess at random on each question, what is the probability that you get at least one question correct?
  5. Math

    A multiple choice quiz contains five question. Each question has four answer choices. Michael is not prepared for the quiz and decides to guess for each question. What is the probability that Michael will get at least one question …
  6. Statistics

    A student guesses blindly on a 20-question multiple choice test. If each question has 4 answer choices (only one of which is correct), what is the probability that the student will answer exactly 10 questions correctly?
  7. Statistics

    A 10 question test is all multiple choice. Each question has four choices. Determine the mean number of questions answered correctly as well as the standard deviation for the number of correct answers if someone were to guess on all …
  8. Statistical concept 68-95-99.7

    1. A student taking a midterm exam in Ancient History comes to two questions pertaining to a lecture that he missed, and so he decides to take a random guess on both questions. One question is true-false and the other is multiple choice …
  9. Stat HW for.

    1. A student taking a midterm exam in Ancient History comes to two questions pertaining to a lecture that he missed, and so he decides to take a random guess on both questions. One question is true-false and the other is multiple choice …
  10. math

    You are writing multiple choice test. Each question has 5 choices, only one of which is correct. You have no idea how to answer three questions. What is the probability that you will get all three of these questions correct if you …

More Similar Questions