Math Problem Statement

A new math-help program comes with a guarantee that it will improve the math scores of 3 in every 10 university students. A university decides to use the program with a cohort of 18 students (selected independently and at random from the student body).

What is the approximate probability that at least 5 of these students will improve their math test scores? (answers rounded to 3 decimals)

0.7220.278    0.5340.4660.667

Solution

This problem can be modeled as a binomial distribution, where:

  • The total number of trials n=18n = 18 (the 18 students),
  • The probability of success (i.e., a student improving their math score) p=0.3p = 0.3 (since 3 in every 10 students improve),
  • The random variable XX represents the number of students who improve their scores, and we are looking for P(X5)P(X \geq 5), which is the probability that at least 5 students improve.

To solve for P(X5)P(X \geq 5), we can first calculate the probability that fewer than 5 students improve their scores, P(X<5)P(X < 5), and subtract this from 1.

Let's calculate this step by step using the binomial probability formula:

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. Then, we sum the probabilities for X=0,1,2,3,4X = 0, 1, 2, 3, 4, and subtract this from 1 to find P(X5)P(X \geq 5).

I'll now calculate this probability.The approximate probability that at least 5 of the 18 students will improve their math scores is 0.667.

Would you like more details on this calculation or have any other questions?

Here are 5 related questions to expand on this concept:

  1. How would the probability change if the number of students increased to 25?
  2. What is the probability that exactly 7 students will improve their math scores?
  3. Can you calculate the expected number of students who will improve their scores?
  4. How does varying the probability of success (p) affect the outcome?
  5. What is the standard deviation of the number of students improving their scores?

Tip: The binomial distribution is useful when you have independent trials with a fixed probability of success, like flipping coins or modeling student performance.

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Math Problem Analysis

Mathematical Concepts

Probability
Binomial Distribution
Random Variables

Formulas

P(X = k) = C(n, k) * p^k * (1 - p)^(n - k)
P(X ≥ 5) = 1 - P(X < 5)

Theorems

Binomial Probability Theorem

Suitable Grade Level

University level (Undergraduate)