Math Problem Statement

Take a guess: A student takes a multiple-choice test that has questions. Each question has four choices. The student guesses randomly at each answer. Let be the number of questions answered correctly. Round the answers to at least four decimal places.

Part: 0 / 20 of 2 Parts Complete Part 1 of 2 (a) P (4)

Solution

This problem involves a binomial distribution, which is applicable when a student guesses randomly on a multiple-choice test. The parameters for a binomial distribution are:

  • nn = the number of trials (questions)
  • pp = the probability of success on each trial (answering a question correctly)
  • XX = the number of questions answered correctly

For this case:

  • Each question has 4 choices, so the probability of guessing correctly is p=14=0.25p = \frac{1}{4} = 0.25.
  • The number of trials nn is the total number of questions.
  • We are asked to find P(X=4)P(X = 4), the probability that the student answers exactly 4 questions correctly.

The probability mass function for a binomial distribution is:

P(X=k)=(nk)pk(1p)nkP(X = k) = \binom{n}{k} p^k (1 - p)^{n - k}

Where:

  • (nk)\binom{n}{k} is the binomial coefficient, representing the number of ways to choose kk successes (correct answers) out of nn trials (questions).
  • pp is the probability of success.
  • kk is the number of correct answers we are calculating the probability for.

To provide a concrete answer, I need the total number of questions nn. Could you provide that detail?

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Math Problem Analysis

Mathematical Concepts

Binomial Distribution
Probability

Formulas

P(X = k) = C(n, k) * p^k * (1 - p)^(n - k)
C(n, k) = n! / (k! * (n - k)!)

Theorems

Binomial Probability Theorem

Suitable Grade Level

Grades 10-12