Math Problem Statement
In the United States, voters who are neither Democrat nor Republican are called Independent. It is believed that 13% of voters are Independent. A survey asked 34 people to identify themselves as Democrat, Republican, or Independent.
A. What is the probability that none of the people are Independent?
Probability =
B. What is the probability that fewer than 4 are Independent?
Probability =
C. What is the probability that more than 2 people are Independent?
Probability =
Solution
Given:
- The probability of a voter being Independent, .
- The number of people surveyed, .
This is a binomial probability problem where the probability of exactly Independents in trials is given by:
Let's solve each part.
Part A: Probability that none of the people are Independent
This is the probability that .
Calculating this:
Part B: Probability that fewer than 4 are Independent
This is the probability that , or .
Each term is calculated as:
Summing these probabilities gives .
Part C: Probability that more than 2 people are Independent
This is the probability that , which can be calculated as:
From Part B, we already know , so:
Final Answers
A.
B.
C.
Would you like a more detailed breakdown of the calculations?
Questions for Practice:
- How would the probabilities change if the survey size were 50 people instead of 34?
- What if the percentage of Independents was 20% instead of 13%?
- How is the binomial distribution related to other probability distributions?
- How would we calculate the expected number of Independents in a survey of 34 people?
- What is the standard deviation of the number of Independents in this survey?
Tip: In a binomial distribution, for probabilities of events with many trials, use a normal approximation when and are both greater than 5.
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Math Problem Analysis
Mathematical Concepts
Probability
Binomial Distribution
Formulas
Binomial probability formula: P(X = k) = C(n, k) * p^k * (1 - p)^(n - k)
Complement rule for probability: P(X > k) = 1 - P(X <= k)
Theorems
Binomial Theorem
Suitable Grade Level
Grades 10-12
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