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According to a survey of 2000 home owners, 800 of them own homes with three bedrooms, and 600 of them own homes with four bedrooms. If one home owner is selected at random from these 2000 home owners, find the probability that this home owner owns a house that has three or four bedrooms. Explain why this probability is not equal to \(1.0\)

Short Answer

Expert verified
The probability that a randomly selected homeowner from the survey owns a house with either three or four bedrooms is 0.7 or 70%.

Step by step solution

01

Identify the Total Outcomes

The total number of outcomes in an event is the total number of homeowners surveyed, which is 2000.
02

Identify Favorable Outcomes for Each Event

The favorable outcomes for corresponding events are: homeowners owning three-bedroom houses which is 800 and homeowners owning four-bedroom houses which is 600.
03

Calculate Individual Probabilities

Probability of a homeowner owning a three bedroom house is the ratio of homeowners with three-bedroom houses to total homeowners. Which is \(\frac{800}{2000}=0.4\). Similarly, probability of a homeowner owning a four bedroom house is \(\frac{600}{2000}=0.3\)
04

Add the Probabilities

To find the probability that a homeowner owns a house with either three or four bedrooms, we add the individual probabilities. So, Probability (three or four bedrooms) = Probability (three bedrooms) + Probability (four bedrooms) = 0.4 + 0.3 = 0.7.
05

Explain why the Total Probability is not 1

The total probability is not 1 (or 100%) because not all homeowners have either a three or four bedroom house. There are other homeowners who have either less than three or more than four bedrooms. Hence the combined probability is less than 1.

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Key Concepts

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

Survey analysis
Understanding survey analysis helps us to make predictions based on collected data. In our exercise, a survey of 2000 homeowners gives us insights into housing preferences and distribution.

A survey collects responses to form a sample that reflects the larger population. In this case, we surveyed 2000 people to learn about their home sizes.
  • This survey aims to understand how many homes have three and four bedrooms.
  • The responses provide information on 800 homes with three bedrooms and 600 homes with four bedrooms.
This data is the foundation for calculating probabilities about housing features in the community.
Probability calculation
Probability tells us how likely an event is to happen. Calculating probability involves comparing favorable outcomes to the entire sample space.

In our problem, we need to find the likelihood that a randomly selected homeowner owns a house with either three or four bedrooms. This involves a few steps:
  • The total number of outcomes, or sample space, is the total number of people, which is 2000.
  • The favorable outcomes for owning a three-bedroom house is 800, and for owning a four-bedroom house is 600.
  • Individual probabilities are calculated as fractions: Probability for three bedrooms = \(\frac{800}{2000} = 0.4\) Probability for four bedrooms = \(\frac{600}{2000} = 0.3\)
These fractions represent the likelihood of picking a homeowner with a specific bedroom count from the survey.
Event outcomes
Events in probability refer to possible results from an experiment or survey. Here, the events are owning a three-bedroom home or a four-bedroom home.

When dealing with such events, it is important to focus on favorable outcomes:
  • Owning a three-bedroom home involves 800 favorable outcomes, which signifies 800 people fit this criteria.
  • Owning a four-bedroom home has 600 favorable outcomes, relating to 600 homeowners with such homes.
To find the probability of either event happening (a three or four-bedroom home), the probabilities are simply added together: \[0.4 + 0.3 = 0.7\] Thus, there is a 70% chance that a selected homeowner from the survey has a house with either three or four bedrooms.
Three and four bedrooms probability
Understanding why the total probability is not 1 is crucial in probability studies. When the probability is calculated, it accounts only for surveyed outcomes.

In our result, we found a probability of 0.7 for three or four bedrooms combined. However, this does not account for all possible outcomes (all possible house sizes) outside these measurements.
  • Some homeowners may have houses with less than three bedrooms.
  • Others may possess homes with more than four bedrooms.
This is why the probability is less than 1; it doesn’t cover all possibilities. The probability value of 0.7 implies that 70% of cases in these categories combined, while 30% remains in other categories not highlighted in the exercise.

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