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Based on data from the Statistical Abstract of the United States, 112 th Edition, only about \(14 \%\) of senior citizens \((65\) years old or older) get the flu each year. However, about \(24 \%\) of the people under 65 years old get the flu each year. In the general population, there are \(12.5 \%\) senior citizens \((65\) years old or older). (a) What is the probability that a person selected at random from the general population is a senior citizen who will get the flu this year? (b) What is the probability that a person selected at random from the general population is a person under age 65 who will get the flu this year? (c) Answer parts (a) and (b) for a community that has \(95 \%\) senior citizens. (d) Answer parts (a) and (b) for a community that has \(50 \%\) senior citizens.

Short Answer

Expert verified
(a) 1.75%, (b) 21% in general population; (a) 13.3%, (b) 1.2% in 95% senior community; (a) 7%, (b) 12% in 50% senior community.

Step by step solution

01

Understanding the Problem

We need to find the probability that a randomly selected person from the population meets specific conditions related to age and flu occurrence. We will solve this problem by considering different proportions of senior citizens in the population and using the given flu incidence percentages.
02

Calculate Probability for Part (a) with General Population

For part (a), the probability that a person is a senior citizen and gets the flu is calculated by multiplying the probability of being a senior citizen by the probability of a senior citizen getting the flu. Given that only 14% of senior citizens get the flu and 12.5% of the population are senior citizens, the calculation is: \[ P(\text{Senior getting flu}) = 0.125 \times 0.14 = 0.0175 \text{ or } 1.75\% \]
03

Calculate Probability for Part (b) with General Population

For part (b), the probability that a randomly chosen person is under 65 and gets the flu is calculated by first finding the probability of not being a senior (i.e., 1 - 12.5%) and the probability of under 65 getting the flu (24%). \[ P(\text{Under 65 getting flu}) = (1 - 0.125) \times 0.24 = 0.875 \times 0.24 = 0.21 \text{ or } 21\% \]
04

Adjust Calculations for Community with 95% Senior Citizens

For this part, the probability of a senior citizen getting the flu is calculated as before but using 95%, and the probability of under 65 is proportionately lower (5%).For a community with 95% senior citizens, \[ P(\text{Senior getting flu}) = 0.95 \times 0.14 = 0.133 \text{ or } 13.3\% \]For under 65:\[ P(\text{Under 65 getting flu}) = 0.05 \times 0.24 = 0.012 \text{ or } 1.2\% \]
05

Adjust Calculations for Community with 50% Senior Citizens

In a hypothetical community with 50% senior citizens, calculate similarly for each group:For senior citizens:\[ P(\text{Senior getting flu}) = 0.5 \times 0.14 = 0.07 \text{ or } 7\% \]For people under 65:\[ P(\text{Under 65 getting flu}) = 0.5 \times 0.24 = 0.12 \text{ or } 12\% \]

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Key Concepts

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

Conditional Probability
Conditional probability is a way to measure the likelihood of an event occurring, given that another event has already happened. It's a foundational concept in probability theory that's often used to make informed decisions based on known information. Think of it as narrowing the field of possibilities. For example, if you know it’s raining, the probability that someone has an umbrella is higher.

In the context of this exercise, calculating the probability that a senior citizen gets the flu involves understanding that the flu occurrence is contingent on the person being a senior. We compute it by multiplying the likelihood of being a senior (about 12.5% of the population) by the probability that a senior gets the flu (14%). Similarly, for those under 65, the calculation involves their proportion in the general population and their probability of contracting the flu (24%).

These probabilities give us insights into how such conditions affect flu incidences in different population segments. It's a useful tool in statistical inference and real-world applications, such as healthcare planning.
Population Proportions
Population proportions refer to the fraction of the total population that possesses a certain characteristic. In probability and statistics, understanding population proportions is crucial, especially when calculating probabilities for conditions across different groups within a population.

For instance, in the exercise, the senior citizen population proportion is 12.5%. This figure helps in understanding what portion of the population you’re dealing with when calculating the probability of contracting the flu for this age group.
  • This proportion directly impacts probabilities. For instance, if the proportion of seniors increases, so does their likelihood of higher flu rates in that group, if other factors remain constant.
  • Likewise, a shift in population proportions would affect the computations for flu incidences in non-senior populations.
Changes in these proportions can occur in specific communities, thereby altering results. For example, communities with 95% senior citizens compared to 50% have vastly different exposure levels to flu within the senior demographic. These considerations help in public health assessment and resource allocation.
Flu Incidence
Flu incidence refers to the rate at which new cases of flu occur in a specific population during a particular time period. It's an important measure for understanding the spread of the flu and devising strategies to combat it.

In this exercise, flu incidence is used as a known probability for different age groups: 14% for seniors and 24% for those under 65. These figures reflect past health data and help in calculating expected cases assuming no change in vaccines or healthcare interventions.

Measuring flu incidence assists in predicting the healthcare needs of a population and in planning interventions like vaccination campaigns.
  • It provides insight into which groups are at higher risk, guiding targeted health strategies and policies.
  • For instance, higher incidence among those under 65 might indicate a need for increased awareness or immunization drives in that group.
Understanding flu incidence and its calculations allows health authorities to better manage resources, advising communities on preventive measures necessary to reduce the spread of influenza.

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Most popular questions from this chapter

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