/*! 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 193 The probability that an individu... [FREE SOLUTION] | 91Ó°ÊÓ

91Ó°ÊÓ

The probability that an individual recovers from an illness in a one-week time period without treatment is 0.1 . Suppose that 20 independent individuals suffering from this illness are treated with a drug and 4 recover in a one- week time period. If the drug has no effect, what is the probability that 4 or more people recover in a one-week time period?

Short Answer

Expert verified
The probability that 4 or more people recover is approximately 0.1329.

Step by step solution

01

Identify the appropriate probability distribution

Since we are dealing with a fixed number of independent trials (20 people) and a binary outcome (recovery or not), we should use the binomial distribution. The probability of recovery without treatment is given as \( p = 0.1 \), so we can assume this in the case where the drug has no effect.
02

Define the binomial probability parameters

In this scenario, the number of trials is \( n = 20 \) and the probability of success (recovery) for each trial is \( p = 0.1 \). We will calculate the probability of 4 or more recoveries, i.e., \( P(X \geq 4) \).
03

Calculate cumulative probability of fewer than 4 recoveries

The cumulative probability of fewer than 4 recoveries (0, 1, 2, or 3 recoveries) can be found by summing the individual binomial probabilities: \( P(X = 0) + P(X = 1) + P(X = 2) + P(X = 3) \).
04

Use the binomial probability formula

The binomial probability formula is \( P(X = k) = \binom{n}{k} p^k (1-p)^{n-k} \). We calculate this for \( k = 0, 1, 2, 3 \) using \( n = 20 \) and \( p = 0.1 \).
05

Calculate \( P(X = 0) \)

Use the formula: \( P(X = 0) = \binom{20}{0} (0.1)^0 (0.9)^{20} \). Simplify and calculate the result, \( P(X = 0) \approx 0.1216 \).
06

Calculate \( P(X = 1) \)

Use the formula: \( P(X = 1) = \binom{20}{1} (0.1)^1 (0.9)^{19} \). Simplify and calculate the result, \( P(X = 1) \approx 0.2702 \).
07

Calculate \( P(X = 2) \)

Use the formula: \( P(X = 2) = \binom{20}{2} (0.1)^2 (0.9)^{18} \). Simplify and calculate the result, \( P(X = 2) \approx 0.2852 \).
08

Calculate \( P(X = 3) \)

Use the formula: \( P(X = 3) = \binom{20}{3} (0.1)^3 (0.9)^{17} \). Simplify and calculate the result, \( P(X = 3) \approx 0.1901 \).
09

Find the cumulative probability of fewer than 4 recoveries

Add the probabilities from Steps 5 through 8: \( P(X < 4) = P(X = 0) + P(X = 1) + P(X = 2) + P(X = 3) \approx 0.1216 + 0.2702 + 0.2852 + 0.1901 = 0.8671 \).
10

Calculate the probability of 4 or more recoveries

Since we have calculated \( P(X < 4) \), we find \( P(X \geq 4) = 1 - P(X < 4) \approx 1 - 0.8671 = 0.1329 \).

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 Theory
Probability theory is a branch of mathematics focused on the analysis and understanding of random phenomena. It offers the mathematical foundation that helps us model and predict the likelihood of different outcomes. This is particularly useful in cases where multiple outcomes are possible, each with their own probability.

In the given exercise, probability theory is utilized to evaluate the likelihood of four or more people recovering from an illness without any effect from the treatment. The scenario uses basic concepts of probability to figure out a solution. For this task, we're primarily concerned with the probability that describes the event of fewer than four people recovering. This is calculated using the binomial probability formula. However, probability theory is vast, and understanding fundamental ideas like sample spaces, events, and probability functions will enrich your comprehension of this concept.
  • A sample space is the set of all possible outcomes.
  • An event is a specific outcome or a set of outcomes within the sample space.
  • A probability function assigns a likelihood to each event.
By mastering these basics, students can approach more complex probability problems with confidence.
Statistical Analysis
Statistical analysis is the process of gathering and analyzing data to identify patterns or trends and make informed decisions. It is essential in various fields, including science, business, and healthcare. This analysis helps us interpret the data logically and derive meaningful conclusions.

In this exercise, statistical analysis is used to interpret and solve the problem of determining the number of people recovering from an illness when subjected to a trial. By applying the binomial distribution, we assume that each trial or observation is independent and follows a certain distribution, allowing us to calculate probabilities effectively. Statistical analysis requires setting up a model, testing hypotheses, and using appropriate statistical methods, like the binomial distribution, to make deductions.

The provided exercise depicts a binary outcome setup (recovery or not), which is analyzed through statistical tools and techniques to estimate the probability of certain recovery numbers. Good statistical practice ensures that results are accurate, reproducible, and meaningful.
Independent Trials
Understanding independent trials is crucial when working with probability and statistics. Independent trials refer to a series of experiments or observations where the outcome of one does not affect the others. This concept is fundamental when applying the binomial distribution, as seen in our exercise.

We assume that each person's recovery from illness is not influenced by anybody else's recovery. This independence allows us to use statistical models that consider each person as a separate trial with the same probability of success (or recovery).
  • Each trial has the same probability of occurrence.
  • Outcomes of one trial do not impact others.
  • In our context, each person represents a separate trial.
By ensuring that trials are independent, the mathematical model remains valid, allowing us to make sound conclusions about the probability of recovery. Independent trials form the backbone of various probability distributions, making them essential to study and comprehend thoroughly.

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

Orders arrive at a Web site according to a Poisson process with a mean of 12 per hour. Determine the following: (a) Probability of no orders in five minutes. (b) Probability of 3 or more orders in five minutes. (c) Length of a time interval such that the probability of no orders in an interval of this length is 0.001 .

A player of a video game is confronted with a series of opponents and has an \(80 \%\) probability of defeating each one. Success with any opponent is independent of previous encounters. Until defeated, the player continues to contest opponents. (a) What is the probability mass function of the number of opponents contested in a game? (b) What is the probability that a player defeats at least two opponents in a game? (c) What is the expected number of opponents contested in a game? (d) What is the probability that a player contests four or more opponents in a game? (e) What is the expected number of game plays until a player contests four or more opponents?

The number of surface flaws in plastic panels used in the interior of automobiles has a Poisson distribution with a mean of 0.05 flaw per square foot of plastic panel. Assume that an automobile interior contains 10 square feet of plastic panel. (a) What is the probability that there are no surface flaws in an auto's interior? (b) If 10 cars are sold to a rental company, what is the probability that none of the 10 cars has any surface flaws? (c) If 10 cars are sold to a rental company, what is the probability that at most 1 car has any surface flaws? .

A trading company uses eight computers to trade on the New York Stock Exchange (NYSE). The probability of a computer failing in a day is \(0.005,\) and the computers fail independently. Computers are repaired in the evening, and each day is an independent trial. (a) What is the probability that all eight computers fail in a day? (b) What is the mean number of days until a specific computer fails? (c) What is the mean number of days until all eight computers fail on the same day?

Patient response to a generic drug to control pain is scored on a 5 -point scale where a 5 indicates complete relief. Historically, the distribution of scores is $$ \begin{array}{lllll} 1 & 2 & 3 & 4 & 5 \\ 0.05 & 0.1 & 0.2 & 0.25 & 0.4 \end{array} $$ Two patients, assumed to be independent, are each scored. (a) What is the probability mass function of the total score? (b) What is the probability mass function of the average score?

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.