/*! This file is auto-generated */ .wp-block-button__link{color:#fff;background-color:#32373c;border-radius:9999px;box-shadow:none;text-decoration:none;padding:calc(.667em + 2px) calc(1.333em + 2px);font-size:1.125em}.wp-block-file__button{background:#32373c;color:#fff;text-decoration:none} Problem 13 An American Society of Investors... [FREE SOLUTION] | 91Ó°ÊÓ

91Ó°ÊÓ

An American Society of Investors survey found 30 percent of individual investors have used a discount broker. In a random sample of nine individuals, what is the probability: a. Exactly two of the sampled individuals have used a discount broker? b. Exactly four of them have used a discount broker? c. None of them have used a discount broker?

Short Answer

Expert verified
a) 0.2643; b) 0.2274; c) 0.0404

Step by step solution

01

Understand the Problem

We are dealing with a binomial probability problem. We have a fixed number of trials (9 individuals), each of whom can be classified as having used a discount broker or not. The probability of an individual having used a discount broker is 0.30.
02

Define the Binomial Distribution

For a binomial distribution, we define \( n \) as the number of trials (9 individuals), \( p \) as the probability of success (a person using a discount broker, which is 0.30), and \( X \) as the random variable representing the number of successes.
03

Calculate Probability for Exactly Two

Use the binomial probability formula: \[ P(X = k) = \binom{n}{k} p^k (1-p)^{n-k} \]For exactly 2 individuals, substitute: \( n = 9 \), \( k = 2 \), and \( p = 0.30 \):\[ P(X = 2) = \binom{9}{2} (0.30)^2 (0.70)^7 \]Calculate:\[ \binom{9}{2} = 36 \]\[ P(X = 2) = 36 \times (0.09) \times (0.0823543) = 0.2643 \]
04

Calculate Probability for Exactly Four

Again, use the binomial formula for exactly 4 individuals:\[ P(X = 4) = \binom{9}{4} (0.30)^4 (0.70)^5 \]Calculate:\[ \binom{9}{4} = 126 \]\[ P(X = 4) = 126 \times (0.0081) \times (0.16807) = 0.2274 \]
05

Calculate Probability for None

In this case, we need the probability that none (0 individuals) have used a discount broker:\[ P(X = 0) = \binom{9}{0} (0.30)^0 (0.70)^9 \]Calculate:\[ \binom{9}{0} = 1 \]\[ P(X = 0) = 1 \times 1 \times (0.0403536) = 0.0404 \]
06

Verify and Summarize Results

We've calculated the probabilities for each scenario using the binomial probability formula: a) Probability exactly two = 0.2643 b) Probability exactly four = 0.2274 c) Probability none = 0.0404

Unlock Step-by-Step Solutions & Ace Your Exams!

  • Full Textbook Solutions

    Get detailed explanations and key concepts

  • Unlimited Al creation

    Al flashcards, explanations, exams and more...

  • Ads-free access

    To over 500 millions flashcards

  • Money-back guarantee

    We refund you if you fail your exam.

Over 30 million students worldwide already upgrade their learning with 91Ó°ÊÓ!

Key Concepts

These are the key concepts you need to understand to accurately answer the question.

Probability Calculations
Probability calculations in the context of binomial distribution is all about finding the likelihood of a certain number of successes in a fixed number of trials. In our exercise scenario, we consider 9 individuals, and the probability they have used a discount broker is set at 0.30. When we try to calculate the probability of exactly 2 out of these 9 individuals having used a discount broker, it becomes essential to use the binomial formula.

This formula helps in finding the probability of 'k' successes in 'n' trials, where each trial is independent. It is given by:
  • \[ P(X = k) = \binom{n}{k} p^k (1-p)^{n-k} \]
Here, \( \binom{n}{k} \) is a binomial coefficient representing the number of ways in which k successes can occur in n trials. The term \( p^k \) is the probability of success raised to the power of k, and \((1-p)^{n-k}\) is the probability of the remaining trials being failures.

By substituting the values of n, k, and p, we can determine the probability for 2 successes, using similar steps for different scenarios like 4 or 0 successes. This process is fundamental to understanding and performing probability calculations in statistics.
Random Sampling
Random sampling is a critical concept in statistics as it allows for unbiased representation of a population. In our exercise, we picked a sample of 9 individuals randomly to determine how many have used a discount broker. Random sampling ensures that every individual in the population has an equal chance of being selected, which in this case, provides a fair representation of all investors.

By using random sampling in exercises like these, we reduce biases and improve the reliability of our statistical predictions. When fitting our scenario to a binomial distribution, it presumes that each individual is selected independently. This is vital to using the binomial distribution accurately as any dependencies could skew the results and affect probability calculations.

Therefore, understanding the nature of your sample and ensuring its randomness is crucial in obtaining true insights from statistical analysis.
Statistical Analysis
Statistical analysis involves interpreting data to make informed decisions and predictions. Our exercise exemplifies basic statistical analysis using the binomial distribution to understand investor behavior. Once we calculate probabilities for scenarios like exactly 2 or 4 individuals using discount brokers, or none at all, we're actually engaging in statistical analysis.

This helps in developing insights about investor trends and how commonly discount brokers are used. The accuracy of our probabilities, influenced by elements like sample size and randomness, directly affects the reliability of our conclusions.

  • Statistical analysis aids in identifying patterns and making predictions based on historical data.
  • It is crucial for businesses to make strategic decisions based on accurate and comprehensive analysis.
Understanding the theory behind these computations enables us to apply them in real-world analysis, enhancing our decision-making processes. By leveraging these methods, analytical skills in conjunction with probability theory can greatly impact data-driven strategies in fields like finance and beyond.

One App. One Place for Learning.

All the tools & learning materials you need for study success - in one app.

Get started for free

Most popular questions from this chapter

Thirty percent of the population in a southwestern community are Spanish- speaking Americans. A Spanish-speaking person is accused of killing a non- Spanish-speaking American. Of the first 12 potential jurors, only 2 are Spanish-speaking Americans, and 10 are not. The defendant's lawyer challenges the jury selection, claiming bias against her client. The government lawyer disagrees, saying that the probability of this particular jury composition is common. What do you think?

A recent survey by the American Accounting Association revealed 23 percent of students graduating with a major in accounting select public accounting. Suppose we select a sample of 15 recent graduates. a. What is the probability two select public accounting? b. What is the probability five select public accounting? c. How many graduates would you expect to select public accounting?

A recent CBS News survey reported that 67 percent of adults felt the U.S. Treasury should continue making pennies. Suppose we select a sample of fifteen adults. a. How many of the fifteen would we expect to indicate that the Treasury should continue making pennies? What is the standard deviation? b. What is the likelihood that exactly 8 adults would indicate the Treasury should continue making pennies? c. What is the likelihood at least 8 adults would indicate the Treasury should continue making pennies?

The Bank of Hawaii reports that 7 percent of its credit card holders will default at some time in their life. The Hilo branch just mailed out 12 new cards today. a. How many of these new cardholders would you expect to default? What is the standard deviation? b. What is the likelihood that none of the cardholders will default? c. What is the likelihood at least one will default?

A manufacturer of computer chips claims that the probability of a defective chip is .002. The manufacturer sells chips in batches of 1000 to major computer companies such as Dell and Gateway. a. How many defective chips would you expect in a batch? b. What is the probability that none of the chips are defective in a batch? c. What is the probability at least one chip is defective in a batch?

See all solutions

Recommended explanations on Math Textbooks

View all explanations

What do you think about this solution?

We value your feedback to improve our textbook solutions.

Study anywhere. Anytime. Across all devices.