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8th grade / Statistics / Continuous data / Continuous grouped data / Grouped frequency table: midpoint
Continuous data can be represented in a "Grouped frequency table" where each class (group) covers the data points within a certain range, and the classes together cover the entire range of the data.
Grouped frequency tables are useful when there are so many raw data points that discrete values would become impossible. A limitation of continuous data is that individual data points are lost so that calculations of the mean, mode or range of the original discrete data points becomes impossible. Instead techniques have been developed to approximate these values for continuous data.
The mean of grouped continuous data can be approximated by finding the midpoint for each class multiplied by the frequency of that class and adding those values then dividing by the total frequency count of all the classes.
The midpoint is calculated by adding the highest number in a range to the lowest number and dividing by 2. So if a grouped frequency table has the classes: 1-10, 11-20, 21-30, and you are asked for the midpoint of the range 21-30, the calculation is 21 + 30 / 2 which is 25.5.
In this topic you are asked to find the midpoint for a specified class in a series of grouped frequency tables. There are 8 question/answer pairs in the lessons, and an additional 8 question/answer pairs in all the games and tests.
With these interactive math lessons you will be learning "Grouped frequency table: midpoint" from
8th grade / Statistics / Continuous data in 3 easy steps. The math in our lessons consists of 8 questions that ask you to identify the correct midpoint for the specified range in each grouped frequency table.
There are 3 easy math lesson activities in this "Grouped frequency table: midpoint" tutorial. These activities progress step by step to help you the learner gradually master this math topic. The activities are based on "3 stage questioning", a method of learning that quickly and easily builds your confidence as you work through the short series of lessons that strengthen your knowledge of the math that you want to learn.
When you have completed the tutorial for a topic, you should try some of our games before finally doing the test for your chosen topic. See the Help box below for detailed instructions on how to use the lesson activities to help you learn your math more easily.
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You start the tutorial with a lesson that introduces the math you will be learning. You will see a set of questions one at a time, and for each question you will see the written answer and also hear the answer to that question.
Repeat the question/answer by clicking on the brown speaker sign. Repeat the question/answer and expand the question graphic by clicking on the question box. Move between questions using the arrow buttons below the question. If there is additional information available for your chosen topic, the "i" button on the left upright bar will be brown on white. Click on the button to load the additional lesson information into the main interface.
This lesson moves on from the "Introduction" lesson and offers you two possible answers to each question. So, you will see a question then a voice will ask "Is this ... or is it ..." and you will have to choose which of the answers is the one that matches the question.
You choose an answer by clicking or tapping on one of the two answer boxes below the question. You can play the audio for each answer again by clicking on the speaker icon beside the written answer (if robot speech is available and enabled). The program will let you know each time whether you answered correctly. A star will light up red for a wrong answer or white/black for a correct answer.
This lesson asks you the questions in a random order compared to the introduction. At the end of the lesson, you can choose whether to repeat the lesson or move on to the next one.
The final lesson of the tutorial shows you multiple possible answers for each question - you must choose the correct one. You are asked a question and below it are a list of two, three, or four possible written/numeric answers from this topic. Pressing the speaker icon will play the math audio for that answer.
For each picture, click on the answer that matches the question. The program will tell you whether you are right or not. As with the Either / Or activity a system of stars indicate your right and wrong answers. The What is it? lesson will show you all the questions you learned in the Introduction but in a random order.
When you complete the "What is it?" lesson, you can choose whether to go on to play some games with this topic, or whether you want to repeat some or all of the lesson activities in this tutorial. You should expect to get 80% of the answers correct in most of the activities before trying some of the Math games with this topic.
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