Yahoo Answers is shutting down on May 4th, 2021 (Eastern Time) and beginning April 20th, 2021 (Eastern Time) the Yahoo Answers website will be in read-only mode. There will be no changes to other Yahoo properties or services, or your Yahoo account. You can find more information about the Yahoo Answers shutdown and how to download your data on this help page.

statistics problem: there are 20 multiple choice questions on a test and each and 4 possible answers.?

You need 10 right to pass. what s the likelihood if you guess at every questions, you will pass? What is the number of questions you can expect to get correct?

5 Answers

Relevance
  • Leltos
    Lv 5
    1 decade ago
    Favorite Answer

    Number of questions you expect to get correct = 20/4 = 5

    Odds of getting a question wrong = 3/4

    Odds of getting a question right = 1/4

    Different ways of getting R questions right = 20 C R

    Odds of getting R questions right = 20CR * (1/4)^R * (3/4)^(20-R)

    Odds of passing = 1 - odds of getting less than 10

    Odds of getting 0-9 right (using excel)

    = POWER(1/4, X) * POWER(3/4, 20-X) *FACT(20)/FACT(X)/FACT(20-X)

    0.003171212

    0.021141413

    0.066947808

    0.133895615

    0.189685455

    0.202331152

    0.168609293

    0.112406195

    0.060886689

    0.027060751

    = 0.986135583 chance of failing

    Chance of passing = 1 - 0.986135583

    = 0.013864

    Not very high.

  • 1 decade ago

    When you guess on a problem that has four choises you have a 1 to 4 chance. So you could get 5 questions right, if you guessed all of em.

  • 1 decade ago

    probability of getiing it right = 1/4

    so you would expect to get 5 right

    likelyhood of getting ten right is 1/2 the likely hood of getting 5 right

    =(1/4)/2

    = 1/8

    hope this helps

  • Smiles
    Lv 4
    1 decade ago

    Probability, huh?

  • How do you think about the answers? You can sign in to vote the answer.
  • 1 decade ago

    dont know

Still have questions? Get your answers by asking now.