Math Problem Statement

A study reports that 59% of Americans support increased funding for public schools. If 4 Americans are chosen at random, what is the probability that:

Give all answers as decimals rounded to three places.

a) All 4 of them support increased funding for public schools? 

b) None of the 4 support increased funding for public schools? 

c) At least one of the 4 support increased funding for public schools?

Solution

To solve these problems, we'll use the binomial probability formula, which is given by:

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

where:

  • nn is the number of trials,
  • kk is the number of successful trials,
  • pp is the probability of success on an individual trial,
  • (nk)\binom{n}{k} is the binomial coefficient.

Given:

  • p=0.59p = 0.59 (probability that one American supports increased funding),
  • 1p=0.411 - p = 0.41 (probability that one American does not support increased funding),
  • n=4n = 4.

Part (a)

Problem: All 4 of them support increased funding for public schools.

Solution: Here, k=4k = 4.

P(X=4)=(44)(0.59)4(0.41)0=1×(0.59)4×1=(0.59)4P(X = 4) = \binom{4}{4} (0.59)^4 (0.41)^0 = 1 \times (0.59)^4 \times 1 = (0.59)^4

Calculating (0.59)4(0.59)^4:

(0.59)40.121(0.59)^4 \approx 0.121

Part (b)

Problem: None of the 4 support increased funding for public schools.

Solution: Here, k=0k = 0.

P(X=0)=(40)(0.59)0(0.41)4=1×1×(0.41)4=(0.41)4P(X = 0) = \binom{4}{0} (0.59)^0 (0.41)^4 = 1 \times 1 \times (0.41)^4 = (0.41)^4

Calculating (0.41)4(0.41)^4:

(0.41)40.028(0.41)^4 \approx 0.028

Part (c)

Problem: At least one of the 4 supports increased funding for public schools.

Solution: The probability that at least one supports increased funding is the complement of the probability that none support increased funding.

P(at least one)=1P(X=0)P(\text{at least one}) = 1 - P(X = 0)

Using the result from part (b):

P(at least one)=10.028=0.972P(\text{at least one}) = 1 - 0.028 = 0.972

So, the probabilities are:

  • (a) P(X=4)0.121P(X = 4) \approx 0.121
  • (b) P(X=0)0.028P(X = 0) \approx 0.028
  • (c) P(at least one)0.972P(\text{at least one}) \approx 0.972

Would you like more details on any part of the solution, or do you have any other questions?

Here are 5 questions you might want to ask next:

  1. How do you calculate the mean and variance of a binomial distribution?
  2. What is the probability of exactly 2 out of 4 Americans supporting increased funding?
  3. How does the probability change if the sample size is increased to 10?
  4. What is the difference between binomial and normal distributions?
  5. How can we use a probability distribution table to solve binomial problems?

Tip: Understanding the complement rule (P(at least one)=1P(none)P(\text{at least one}) = 1 - P(\text{none})) can simplify many probability problems.

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Math Problem Analysis

Mathematical Concepts

Probability
Binomial Distribution

Formulas

Binomial probability formula: P(X = k) = binom{n}{k} p^k (1-p)^(n-k)

Theorems

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Suitable Grade Level

High School