/*! This file is auto-generated */ .wp-block-button__link{color:#fff;background-color:#32373c;border-radius:9999px;box-shadow:none;text-decoration:none;padding:calc(.667em + 2px) calc(1.333em + 2px);font-size:1.125em}.wp-block-file__button{background:#32373c;color:#fff;text-decoration:none} Problem 113 The percentage of adult height a... [FREE SOLUTION] | 91Ó°ÊÓ

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The percentage of adult height attained by a girl who is \(x\) years old can be modeled by $$f(x)=62+35 \log (x-4)$$ where \(x\) represents the girl's age (from 5 to 15 ) and \(f(x)\) represents the percentage of her adult height. Round answers to the nearest tenth of a percent. Approximately what percentage of her adult height has a girl attained at age \(13 ?\)

Short Answer

Expert verified
A girl has attained approximately 93.4% of her adult height at the age of 13.

Step by step solution

01

Understanding the function

The given formula is \(f(x)=62+35 \log (x-4)\), where \(x\) is the girl's age, and \(f(x)\) represents the percentage of her adult height.
02

Substituting the value of age into the function

According to the problem, you need to find out the percentage of adult height a girl has attained at 13 years old. So, substitute \(x = 13\) into the function \(f(x)\). This gives \(f(13)=62+35 \log (13-4)\).
03

Computing the solution

Perform the calculation to get the percentage of her adult height: \(f(13)=62+35 \log (13-4)\). First treat the logarithmic part: \(\log (13-4)\) corresponds to the logarithm base 10 of 9. Continue by multiplying by 35 and adding 62. Finally, you arrive at a numerical result.
04

Rounding off

The problem asks for the answer to the nearest tenth of a percent, so round off the answer obtained in the previous step to the nearest tenth of a percent.

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Key Concepts

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

Modeling Real-World Situations with Functions
Understanding how mathematical functions model real-world situations can dramatically enhance one's ability to solve real-life problems. For instance, consider the question at hand: estimating the percentage of adult height that a young girl has attained at a specific age. This can be accurately mapped using a logarithmic function.

The function in the exercise, \(f(x) = 62 + 35 \log (x - 4)\), serves as a model for predicting growth patterns in girls. This illustrates how algebra can interplay with biology to provide a statistical insight into human development. Here the logarithmic function captures the slowing growth rates as the girl ages - an example of how specific function types are selected to reflect the nature of the data they represent.

In general, when modeling real-world scenarios, it's crucial to identify patterns or behaviors and then choose the suitable type of function—be it linear, quadratic, or logarithmic—to represent the situation mathematically. The function's parameters are then adjusted through data fitting techniques to ensure the model is as accurate as possible.
Solving Logarithmic Equations
Logarithmic equations can often be the key to unlocking problems involving exponential relationships. Solving these equations might involve isolating the logarithmic term and then rewiring the equation into its exponential form.

Consider the step-by-step solution provided for the exercise. The objective is to solve for \(f(13)\), the predicted percent height at age 13. After substituting 13 for x in the equation, you apply arithmetic operations and logarithmic rules. The computations may involve using properties of logarithms, such as \(\log_{10}(AB) = \log_{10}(A) + \log_{10}(B)\), or converting between logarithmic and exponential forms when necessary.

With modern tools and a calculator, solving logarithmic equations has become more accessible. However, it remains important for students to know underlying principals, to both understand the steps a calculator takes and to approach problems that may require algebraic manipulations, like those that cannot be directly calculated.
Interpreting Logarithmic Functions
When analyzing logarithmic functions, interpreting their output in the context of the problem is as important as computing the values. The output of a logarithmic function such as \(f(x) = 62 + 35 \log (x - 4)\) doesn't just give us numbers; it gives us meaningful information about the world—in this case, a girl's growth.

One crucial aspect of interpreting logarithmic functions is understanding the rate of change. Logarithms model scenarios where change occurs rapidly at first and then slows down, a pattern common in many natural processes, like the growth of a child. Logarithmic functions are also used widely in other domains, like measuring sound intensity (decibels) or the acidity of a solution (pH levels).

Hence, interpreting a logarithmic function in context involves relating the rate of growth to the variable of interest (in this case, age) and deciphering what that growth trend means in the real-world situation.
Algebraic Problem-Solving
Algebraic problem-solving encompasses a strategy of steps to simplify and solve equations, whether they are linear, quadratic, or more complex functions like logarithmic equations. It generally involves breaking down the problem, understanding the given variables and how they interrelate, and then systematically solving for the unknowns.

In the case of the provided exercise, you begin by recognizing the variables and constants: the girl's age \(x\), the constant percentages 62 and 35, and the operation of a logarithm on \(x-4\). With these in mind, you substitute known values into the equation and use properties of logarithms to simplify and solve the equation for the desired variable. The problem-solving pathway culminates in rounding off the solution, which is a skill often overlooked but highly significant in ensuring solutions are practical and applicable.

Algebraic problem-solving isn't just about finding answers; it's about developing a logical approach, validating each step through mathematical rules, and ensuring that solutions are not just accurate but also make sense in their specific context.

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Most popular questions from this chapter

Logarithmic models are well suited to phenomena in which growth is initially rapid but then begins to level off. Describe something that is changing over time that can be modeled using a logarithmic function.

Students in a mathematics class took a final examination. They took equivalent forms of the exam in monthly intervals thereafter. The average score, \(f(t),\) for the group after \(t\) months was modeled by the human memory function \(f(t)=75-10 \log (t+1), \quad\) where \(\quad 0 \leq t \leq 12 . \quad\) Use \(\quad\) a graphing utility to graph the function. Then determine how many months elapsed before the average score fell below 65.

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Graph each of the following functions in the same viewing rectangle and then place the functions in order from the one that increases most slowly to the one that increases most rapidly. \(y=x, y=\sqrt{x}, y=e^{x}, y=\ln x, y=x^{x}, y=x^{2}\)

Hurricanes are one of nature's most destructive forces. These low-pressure areas often have diameters of over 500 miles. The function \(f(x)=0.48 \ln (x+1)+27\) models the barometric air pressure, \(f(x),\) in inches of mercury, at a distance of \(x\) miles from the eye of a hurricane. Use an equation to answer this question: How far from the eye of a hurricane is the barometric air pressure 29 inches of mercury? Use the \([\mathrm{TRACE}]\) and \([\mathrm{ZOOM}]\) features or the intersect command of your graphing utility to verify your answer.

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