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Dental Insurance You plan to purchase dental insurance for your three remaining years in school. The insurance makes a one-time payment of \(\$ 1,000\) in case of a major dental repair (such as an implant) or \(\$ 100\) in case of a minor repair (such as a cavity). If you don't need dental repair over the next 3 years, the insurance expires and you receive no payout. You estimate the chances of requiring a major repair over the next 3 years as \(5 \%,\) a minor repair as \(60 \%\) and no repair as \(35 \%\). a. Why is \(X=\) payout of dental insurance a random variable? b. Is \(X\) discrete or continuous? What are its possible values? c. Give the probability distribution of \(X\).

Short Answer

Expert verified
a. X is a random variable because its value depends on uncertain events. b. X is discrete, with possible values of 0, 100, 1000. c. The probability distribution is P(X=1000)=0.05, P(X=100)=0.60, P(X=0)=0.35.

Step by step solution

01

Understanding Random Variable

A random variable is a variable whose possible values are numerical outcomes of a random phenomenon. In this case, the payout of the dental insurance ( X ) depends on uncertain events (major repair, minor repair, or no repair) and thus it is considered a random variable.
02

Determine Discreteness or Continuity

We classify X as discrete or continuous. A discrete random variable has specific, isolated values. Here, X can take on specific payouts: \(1000\), \(100\), or \(0\). These are specific monetary amounts, so X is a discrete random variable.
03

Identify Possible Values

Identify the possible payouts: for a major repair the payout is \(1000\), for a minor repair it is \(100\), and if there's no repair, the payout is \(0\). Thus, the possible values of X are \(0, 100, 1000\).
04

Formulate Probability Distribution

To form the probability distribution, assign probabilities to each outcome as given: \(P(X = 1000) = 0.05\) for a major repair, \(P(X = 100) = 0.60\) for a minor repair, and \(P(X = 0) = 0.35\) if no repair is needed.

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Key Concepts

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

Probability Distribution
A probability distribution is a fundamental concept in probability theory that describes the likelihood of different outcomes for a random variable. In the context of our exercise, the random variable is the dental insurance payout, denoted as \(X\). This random variable can take on specific values depending on the occurrence of certain events over the next three years.

Here’s how it works:
  • The probability distribution assigns a probability to each of these outcomes, reflecting how likely each event is to happen.
  • For our example, the events are the need for a major repair, a minor repair, or no repair, each with assigned probabilities.
This means:
  • The probability \(P(X = 1000)\) of receiving a \\(1000 payout (major repair) is \(5\%\) or 0.05.
  • For a \\)100 payout (minor repair), \(P(X = 100)\) is \(60\%\) or 0.60.
  • Lastly, the probability \(P(X = 0)\) for no payout (no repair) is \(35\%\) or 0.35.
This approach allows us to fully understand and anticipate the chances of different payouts from the dental insurance policy.
Discrete Random Variable
A discrete random variable is a type of random variable that has a countable number of possible values. Unlike continuous random variables that can take any value in a range, discrete random variables are limited to specific outcomes. In our insurance example, \(X\) is a discrete random variable because it only takes certain specific values based on the dental repair events.

Consider the following:
  • The payouts provided by the insurance—\\(1000, \\)100, and \$0—are distinct, separate numbers.
  • These values are not part of a continuous range of numbers; they are isolated points.
  • This defines \(X\) as discrete, highlighting scenarios where each outcome is distinct and intrinsic to the event.
Thus, understanding \(X\) as a discrete random variable helps students predict payment outcomes accurately based on their categorical nature.
Probability Theory
Probability theory is the branch of mathematics that deals with analyzing and understanding random events. It provides the mathematical foundation for working with random variables and distributions, helping us assess uncertainty and chance.

In our exercise, we used probability theory to model and calculate the chance of different payout outcomes for the dental insurance. Applying probability theory involves:
  • Identifying all potential outcomes (major repair, minor repair, no repair).
  • Assessing their likelihood using probability rules.
  • Summing probabilities to ensure they total 1, covering all possible scenarios.
The theory is critical in making predictions about future events based on historical data, helping insurance companies and policyholders assess risk and make informed decisions. In this case, through probability theory, we gain a clearer picture of expected payouts and their associated risks.

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Most popular questions from this chapter

On September \(7,2008,\) the Pittsburgh Pirates lost their 8 2nd game of the 2008 season and tied the \(1933-1948\) Philadelphia Phillies major sport record (baseball, football, basketball, and hockey) for most consecutive losing seasons at \(16 .\) In fact, their losing streak continued until 2012 with 20 consecutive losing seasons. A Major League Baseball season consists of 162 games, so for the Pirates to end their streak, they need to win at least 81 games in a season (which they did in 2013\()\) a. Over the course of the streak, the Pirates have won approximately \(42 \%\) of their games. For simplicity, assume the number of games they win in a given season follows a binomial distribution with \(n=162\) and \(p=0.42 .\) What is their expected number of wins in a season? b. What is the probability that the Pirates will win at least 81 games in a given season? (You may use technology to find the exact binomial probability or use the normal distribution to approximate the probability by finding a \(z\) -score for 81 and then evaluating the appropriate area under the normal curve.) c. Can you think of any factors that might make the binomial distribution an inappropriate model for the number of games won in a season?

Binomial needs fixed \(n\) For the binomial distribution, the number of trials \(n\) is a fixed number. Let \(X\) denote the number of girls in a randomly selected family in Canada that has three children. Let \(Y\) denote the number of girls in a randomly selected family in Canada (that is, the number of children could be any number). A binomial distribution approximates well the probability distribution for one of \(X\) and \(Y\), but not for the other. a. Explain why. b. Identify the case for which the binomial applies and identify \(n\) and \(p\).

For a normal distribution, use Table A, software, or a calculator to find the probability that an observation is a. at least 1 standard deviation above the mean. b. at least 1 standard deviation below the mean. c. within 1 standard deviation of the mean.

For each of the following situations, explain whether the binomial distribution applies for \(X\). a. You are bidding on four items available on eBay. You think that you will win the first bid with probability \(25 \%\) and the second through fourth bids with probability \(30 \%\). Let \(X\) denote the number of winning bids out of the four items you bid on. b. You are bidding on four items available on eBay. Each bid is for \(\$ 70\), and you think there is a \(25 \%\) chance of winning a bid, with bids being independent events. Let \(X\) be the total amount of money you pay for your winning bids.

Checking guidelines In a village having more than 100 adults, eight are randomly selected in order to form a committee of residents. \(40 \%\) of adults in the village are connected with agriculture. a. Verify that the guidelines have been satisfied about the relative sizes of the population and the sample, thus allowing the use of a binomial probability distribution for the number of selected adults connected with agriculture. b. Check whether the guideline was satisfied for this binomial distribution to be reasonably approximated by a normal distribution.

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