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91Ó°ÊÓ

An instructor has graded 19 exam papers submitted by students in a class of 20 students, and the average so far is 70 . (The maximum possible score is 100 .) How high would the score on the last paper have to be to raise the class average by 1 point? By 2 points?

Short Answer

Expert verified
To raise the class average by 1 point, the score on the last paper would have to be 90. To raise the class average by 2 points, the score on the last paper would have to be 110.

Step by step solution

01

Calculate the total score after 19 exams

To find the total score after 19 exams, you have to multiply the current average 70 by 19 students. For this, the formula will look like \(total score_{19} = average_{19} * number_{19}\).
02

Calculate the new desired total to increase the average

Next, you need to calculate the new total scores needed to have an average score of 71 and 72. The number of students will be 20 now as we are including the last exam. The formula will look like this: \(required total score_{20} = average_{20} * number_{20}\). You calculate this twice, once for an average score of 71 and once for an average score of 72.
03

Calculate the score needed on the last exam

The score needed on the last exam paper to raise the class average by 1 or 2 points will be the difference between the required total score for 20 exams and the total score after 19 exams. The formula will look like this: \(score_{last} = required total score_{20} - total score_{19}\). You calculate this twice, once for an average score of 71 and once for an average score of 72.

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Key Concepts

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

Statistics Education
Statistics is a field of mathematics that deals with the collection, analysis, interpretation, and presentation of masses of numerical data. An essential part of statistics education is understanding how to measure central tendencies, such as the mean or average, which is the focal point of the class average calculation exercise.

Understanding averages is crucial because it provides a single value that represents the middle of a data set. In our everyday life, and especially in educational contexts, averages can help compare students' performances, assess teaching efficacy, and make informed decisions based on data. The challenge lies not just in performing mathematical operations, but also in interpreting the results in context and understanding their implications.

For educators and learners alike, developing a strong foundational knowledge in statistics is instrumental for navigating through various academic and professional disciplines, where data interpretation becomes a daily task.
Average Score Determination
The average score determination is a process that involves adding up all the values in a dataset and dividing the sum by the number of values. It’s a measure of central tendency that is often used to find the 'typical' value of a set of numbers. The mathematical formula for the average (or arithmetic mean) of a set of numbers is expressed as \( \text{average} = \frac{\text{sum of values}}{\text{number of values}} \).

In the context of our exercise, the average after grading 19 exams was 70. To find out what score is needed on the 20th exam to raise the average to 71 or 72, we sum the scores of the first 19 exams and add the required score to achieve the new averages. It’s important to partake in this exercise because it teaches students how averages can be influenced and how additional data points affect the overall dataset. This is a fundamental concept in statistics education, with practical implications in real-world scenarios.
Mathematical Problem Solving
Mathematical problem solving is about understanding and working through a problem step-by-step to arrive at a solution. It involves a combination of knowledge, skills, and thought processes. In our exercise, the problem required applying a series of calculations to determine how a single score could raise the class average.

The key steps included calculating the current total score, determining the desired new total to raise the average, and lastly, finding out the score needed on the last exam. Through exercises like these, students not only practice their computational skills but also learn to apply logical reasoning to approach and solve complex problems.

Furthermore, mathematical problem solving encompasses the ability to think critically and make connections between mathematical concepts, such as average determination, and how they are used to solve problems in statistics and beyond. Encouraging the development of these skills helps students grow into adept problem solvers in various contexts.

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Most popular questions from this chapter

A sample of \(n=5\) college students yielded the following observations on number of traffic citations for a moving violation during the previous year: $$ x_{1}=1 \quad x_{2}=0 \quad x_{3}=0 \quad x_{4}=3 \quad x_{5}=2 $$ Calculate \(s^{2}\) and \(s\). 4.16 Give two sets of five numbers that have the same mean but different standard deviations, and give two sets of five numbers that have the same standard deviation but different means.

A sample of concrete specimens of a certain type is selected, and the compressive strength of each specimen is determined. The mean and standard deviation are calculated as \(\bar{x}=3000\) and \(s=500\), and the sample histogram is found to be well approximated by a normal curve. a. Approximately what percentage of the sample observations are between 2500 and 3500 ? b. Approximately what percentage of sample observations are outside the interval from 2000 to 4000 ? c. What can be said about the approximate percentage of observations between 2000 and 2500 ? d. Why would you not use Chebyshev's Rule to answer the questions posed in Parts (a)-(c)?

The San Luis Obispo Telegram-Tribune (November 29,1995 ) reported the values of the mean and median salary for major league baseball players for \(1995 .\) The values reported were \(\$ 1,110,766\) and \(\$ 275,000\). a. Which of the two given values do you think is the mean and which is the median? Explain your reasoning. b. The reported mean was computed using the salaries of all major league players in \(1995 .\) For the 1995 salaries, is the reported mean the population mean \(\mu\) or the sample mean \(\bar{x}\) ? Explain.

An advertisement for the "30-in. Wonder" that appeared in the September 1983 issue of the journal Packaging claimed that the 30 -in. Wonder weighs cases and bags up to \(110 \mathrm{lb}\) and provides accuracy to within \(0.25 \mathrm{oz}\). Suppose that a 50 -oz weight was repeatedly weighed on this scale and the weight readings recorded. The mean value was \(49.5 \mathrm{oz}\), and the standard deviation was \(0.1\). What can be said about the proportion of the time that the scale actually showed a weight that was within \(0.25 \mathrm{oz}\) of the true value of 50 oz? (Hint: Use Chebyshev's Rule.)

O Bidri is a popular and traditional art form in India. Bidri articles (bowls, vessels, and so on) are made by casting from an alloy containing primarily zinc along with some copper. Consider the following observations on copper content (\%) for a sample of Bidri artifacts in London's Victoria and Albert Museum ("Enigmas of Bidri," Surface Engineering [2005]: 333-339), listed in increasing order: \(\begin{array}{llllllllll}2.0 & 2.4 & 2.5 & 2.6 & 2.6 & 2.7 & 2.7 & 2.8 & 3.0 & 3.1\end{array}\) \(\begin{array}{llllllllll}3.2 & 3.3 & 3.3 & 3.4 & 3.4 & 3.6 & 3.6 & 3.6 & 3.6 & 3.7\end{array}\) \(\begin{array}{llllll}4.4 & 4.6 & 4.7 & 4.8 & 5.3 & 10.1\end{array}\) a. Construct a dotplot for these data. b. Calculate the mean and median copper content. c. Will an \(8 \%\) trimmed mean be larger or smaller than the mean for this data set? Explain your reasoning.

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