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a. calculate the constant percentage change for the model. b. interpret the answer to part \(a\) in context. Sleep Time (Women) Until women reach their mid-60s, they tend to get less sleep per night as they age. The average number of hours, in excess of eight hours, that a woman sleeps per night can be modeled as $$ s(w)=2.697\left(0.957^{w}\right) \text { hours } $$ when the woman is \(w\) years of age, \(15 \leq w \leq 64\) (Source: Based on data from the Bureau of Labor Statistics)

Short Answer

Expert verified
The sleep time decreases by 4.3% per year as the woman ages.

Step by step solution

01

Understanding the Model Function

We begin by examining the function given in the exercise: \( s(w) = 2.697 \cdot 0.957^w \). This model describes how the sleep time in excess of eight hours changes with age \( w \). The base of the exponent, \(0.957\), will help us understand the constant percentage change in sleep time as age increases.
02

Identifying the Constant Percentage Change

The base of the exponent \(0.957\) indicates the factor by which sleep changes when age increases by 1 year. To find the percentage change, compute \(0.957 - 1 = -0.043\). This tells us that each additional year decreases the sleep amount by \(4.3\%\).
03

Writing the Mathematical Expression

Express this as a percentage change by considering: \( \text{Change} = 0.957 - 1 = -0.043 \). The negative sign indicates a decrease. Multiply by 100 to convert this into a percentage: \(-0.043 \times 100 = -4.3\%\).
04

Interpretation in Context

The constant percentage change of \(-4.3\%\) implies that for each additional year a woman ages within the specified age range, the amount of sleep beyond eight hours decreases by \(4.3\%\). This highlights the trend of reduced sleep time with increasing age until the mid-60s.

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Key Concepts

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

Understanding Percentage Change
Percentage change is a vital concept in understanding how quantities evolve over time or different conditions. In our example, the function provided, \( s(w) = 2.697 \times 0.957^w \), models the reduction in sleep hours for women as they age. Here, the coefficient 2.697 represents a scaling factor for the initial sleep measurement, while the base 0.957 of the exponent indicates the rate at which sleep changes annually. To quantify this change, the formula \( (0.957 - 1) \times 100 = -4.3\% \) is used. This formula calculates the percentage decrease in sleep amount per year as a woman ages.
  • The negative percentage signifies a decrease.
  • A 4.3% decrease shows a consistent pattern of reduced sleep each year.
Understanding this percentage change helps highlight trends in health and lifestyle as women get older.
Exponential Model Explanation
Exponential models are used to describe processes that change by a consistent percentage rate over equal increments, which is why they're perfect for our sleep study. In the function \( s(w) = 2.697 \times 0.957^w \), the exponent \(w\) indicates that age is the variable affecting sleep. The model is 'exponential' because the sleep duration decreases by the same proportion for each increase in age.The base \(0.957\) in our model is crucial. It is less than 1, indicating a decrease. But it also represents the proportional factor by which sleep is reduced each year. An exponential decay in sleep time is realistic, as physiological changes over age can steadily decrease restful periods.
  • Exponential models can represent both growth (when base > 1) and decay (when base < 1).
  • They provide insights into long-term trends, helpful for making health predictions.
Aging and Sleep Patterns in Women
As women age, their sleep patterns often change, and understanding this helps in adapting better health habits. The model \( s(w) = 2.697 \times 0.957^w \) identifies a decline in the hours of sleep beyond eight, a common benchmark for adequate rest. This decline, quantified at a constant rate of \(4.3\%\), emphasizes how aging affects sleep negatively until mid-60s.Sleep is crucial for overall health, influencing physical and mental well-being. As women age, factors such as hormonal changes, lifestyle adjustments, and even societal roles can contribute to shifts in sleep needs and patterns. Recognizing the natural decline reflected in the model can promote:
  • Awareness among women to prioritize sleep hygiene and health.
  • Research into interventions that might help mitigate sleep loss as women age.
Understanding these patterns is significant for healthcare providers to suggest appropriate lifestyle changes and for women themselves to maintain optimal health.

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Most popular questions from this chapter

The following two functions have a common input, year \(t: R\) gives the average price, in dollars, of a gallon of regular unleaded gasoline, and \(P\) gives the purchasing power of the dollar as measured by consumer prices based on 2010 dollars. a. Using function notation, show how to combine the two functions to create a new function giving the price of gasoline in constant 2010 dollars. b. What are the output units of the new function?

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