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The nation's two biggest cable providers are Comcast Cable Communications, with 21.5 million subscribers, and Time Warner Cable, with 11.0 million subscribers (The New York Times 2007 Almanac). Suppose that management of Time Warner Cable subjectively assessed a probability distribution for \(x\), the number of new subscribers they will obtain over the next year in the state of New York, as follows: $$\begin{array}{cc} \boldsymbol{x} & \boldsymbol{f}(\boldsymbol{x}) \\ 100,000 & .10 \\ 200,000 & .20 \\ 300,000 & .25 \\ 400,000 & .30 \\ 500,000 & .10 \\ 600,000 & .05 \end{array}$$ a. Is this probability distribution valid? Explain. b. What is the probability Time Warner will obtain more than 400,000 new subscribers? c. What is the probability Time Warner will obtain fewer than 200,000 new subscribers?

Short Answer

Expert verified
a. Yes, it is valid. b. 0.15 c. 0.10

Step by step solution

01

Validate the Probability Distribution

To verify the validity of a probability distribution, ensure that the sum of all probabilities equals 1. Add the given probabilities:\[0.10 + 0.20 + 0.25 + 0.30 + 0.10 + 0.05 = 1.00\]Since the sum is 1, this is a valid probability distribution.
02

Probability of More Than 400,000 Subscribers

To find the probability of obtaining more than 400,000 subscribers, add the probabilities of the outcomes where \(x > 400,000\):\[P(x > 400,000) = P(500,000) + P(600,000) = 0.10 + 0.05 = 0.15\]
03

Probability of Fewer Than 200,000 Subscribers

To find the probability of obtaining fewer than 200,000 subscribers, consider the probabilities of the outcomes where \(x < 200,000\):\[P(x < 200,000) = P(100,000) = 0.10\]

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Key Concepts

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

Probability
Probability is a way to measure how likely an event is to occur. It is expressed as a value between 0 and 1, where 0 indicates impossibility and 1 indicates certainty. For example, when Time Warner Cable estimates the likelihood of gaining a certain number of subscribers, they use probabilities to reflect this uncertainty. Each possible outcome of gaining 100,000, 200,000 up to 600,000 subscribers is assigned a probability. Understanding probability helps in making informed decisions based on potential outcomes. For instance, a probability of 0.10 means there is a 10% chance that a certain number of new subscribers will be gained.
To validate a probability distribution, the sum of all probabilities for every possible outcome should be equal to 1. This makes sure the distribution accounts for all potential scenarios. In our exercise, the sum of the probabilities given was exactly 1, making it a valid probability distribution.
Statistical Analysis
Statistical analysis involves collecting and interpreting data to identify patterns and trends. In the context of our exercise, Time Warner Cable uses statistical analysis to predict subscriber growth. They create a probability distribution to help understand and forecast the number of new subscribers they might gain over the next year. This analysis involves steps such as validating the probability distribution and calculating chances of certain events. For example, identifying the probability of getting more than 400,000 subscribers by adding the probabilities of all outcomes greater than 400,000 is a form of this analysis.
Statistical analysis is crucial for businesses because it provides evidence-based predictions. These predictions can guide strategic decisions, such as resource allocation or marketing strategies, to better meet demands or capitalize on opportunities.
Random Variables
A random variable is a numerical description of the outcome of a random phenomenon. In our exercise, the random variable is the number of new subscribers, denoted as \(x\). This variable represents various outcomes, such as the company gaining 100,000 to 600,000 subscribers.Random variables can be discrete or continuous. Our example involves a discrete random variable since the number of subscribers is counted in specific increments.
The value of random variables can change based on different conditions or probabilities. In forming the probability distribution, each possible outcome that our random variable \(x\) could take has an associated probability, like 0.25 for obtaining 300,000 new subscribers. Understanding random variables is key in predicting and analyzing different scenarios of subscriber growth, allowing Time Warner Cable to better assess their future market dynamics.

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