Math Problem Statement

fifty nine percent of us adults think that civil rights for black americans have improved during their lifetime. you randomly select ten us adults. find the probability that the number who think civil rights got black americans have improved during yheir lifetime is exactly two

Solution

This problem is a classic example of a binomial probability problem, where we have two possible outcomes:

  • A person believes civil rights for Black Americans have improved during their lifetime (success).
  • A person does not believe so (failure).

We are given:

  • The probability of success (pp) is 59% or 0.59.
  • The probability of failure (qq) is 1 - 0.59 = 0.41.
  • The number of trials (nn) is 10 (since 10 US adults are randomly selected).
  • We need to find the probability that exactly 2 out of the 10 people think civil rights for Black Americans have improved, which means we are looking for P(X=2)P(X = 2), where XX is the number of successes.

The formula for binomial probability 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, calculated as n!k!(nk)!\frac{n!}{k!(n-k)!},
  • pp is the probability of success,
  • kk is the number of successes (2 in this case),
  • nn is the number of trials (10 in this case).

Step 1: Calculate the binomial coefficient (102)\binom{10}{2}

(102)=10!2!(102)!=10×92×1=45\binom{10}{2} = \frac{10!}{2!(10-2)!} = \frac{10 \times 9}{2 \times 1} = 45

Step 2: Calculate the probability

Now, plug everything into the binomial probability formula:

P(X=2)=45×(0.59)2×(0.41)8P(X = 2) = 45 \times (0.59)^2 \times (0.41)^8

Step 3: Simplify and calculate the result

Let's calculate this:

(0.59)2=0.3481(0.59)^2 = 0.3481 (0.41)8=0.0001069(0.41)^8 = 0.0001069 Now multiply all terms together:

P(X=2)=45×0.3481×0.00010690.001678P(X = 2) = 45 \times 0.3481 \times 0.0001069 \approx 0.001678

So, the probability that exactly 2 out of the 10 people believe civil rights for Black Americans have improved during their lifetime is approximately 0.0017 or 0.17%.


Would you like further details or have any additional questions? Here are some related questions that might interest you:

  1. What happens to the probability if we increase the number of people selected?
  2. How do we interpret the probability when we have such a small value?
  3. Can you explain the concept of binomial distribution in more detail?
  4. What would be the probability if we wanted to know the likelihood that exactly 5 people believe civil rights have improved?
  5. How does the probability change if the belief rate changes to 70% instead of 59%?

Tip: The binomial distribution is most useful when there are a fixed number of independent trials, each with only two possible outcomes, and the probability of success remains constant across trials.

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Math Problem Analysis

Mathematical Concepts

Binomial Probability
Probability Theory
Combinatorics

Formulas

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

Theorems

Binomial Theorem

Suitable Grade Level

Grades 10-12