State exam question on averages (mean), question #1

NGSS Science Videos

This video helps children prepare for state math exams by explaining how to solve a retired (released) question from an actual state exam.     - If you want to copy any of our more than 100 free Google Forms (all with questions and links to free-access educational videos we've made), then please download this free file from TPT and it will give you directions for how to access them: https://www.teacherspayteachers.com/Product/State-Math-Test-questions-and-answers-as-a-Google-Form-2022-Q6-10-V2-11530867   Other free resources we've made:  - For links to many free educational resources, please visit our website (no 3rd party advertising, no subscriptions, no paywalls): https://TestPrepLLC.org/   - For our free apps for Apple's Mac and iPad (collects no data, no advertising, no subscriptions, no paywalls, no in-app purchases), please visit our page on the Apple App Store. These apps include Common Core and State based practice tests in math, and State science exams based on NGSS and State curriculums (all with detailed, colorful explanations): https://apps.apple.com/us/developer/test-prep-llc/id1727786893   Best wishes,  The staff at Test Prep LLC  https://TestPrepLLC.org

Transcript

00:00This video is part of a Google Form quiz that teachers can assign to their students for

00:05homework. After the students submit their answers, then they can play a video like

00:09this one to see the answer explained. We've made more than 100 quizzes as Google Forms

00:15with free access videos, which teachers are welcome to copy for free. To get access to these,

00:21please see the link in the description. This video is based on a question from an

00:26actual state exam. You may have one like this on your state exam. If you've not already watched the

00:32video on how to calculate the average, then we suggest that you view it before watching this

00:37video. A teacher recorded reading scores for three groups, which groups have the same mean score.

00:44We define the mean as the answer to a division problem. In everyday language, we use the word

00:50average instead of the word mean. The word mean is used on math tests and in math books,

00:56but has the same idea and formula as the word average. The mean of a set of numbers

01:02equals the sum of those numbers divided by the number count. Let's start by calculating the mean

01:07of group 1. There are three numbers in this group, so the number count for this set is 3.

01:13The sum of these numbers is the total of 15 plus 11 plus 19. That sum equals 45. Here's the formula for

01:21the mean. The mean equals the sum of the numbers divided by the number count. We substitute the

01:27phrase sum of numbers with 45. We substitute the phrase number count with 3. Then we do the division.

01:3545 divided by 3 equals 15. The mean for this group is 15. Next, let's calculate the mean of group 2.

01:44There are 5 numbers in this group, so the number count for this set is 5. The sum of these numbers

01:50is the total of 12 plus 14 plus 20 plus 14 plus 20. That sum equals 80. Here's the formula for the mean.

01:59The mean equals the sum of the numbers divided by the number count.

02:03We substitute the phrase sum of numbers with 80. We substitute the phrase number count with 5.

02:10Then we do the division. 80 divided by 5 equals 16. The mean for this group is 16. Next,

02:17let's calculate the mean of group 3. There are four numbers in this group, so the number count for this

02:23set is 4. The sum of these numbers is the total of 13 plus 19 plus 14 plus 14. That sum equals

02:3260. Here's the formula for the mean. The mean equals the sum of the numbers divided by the number count.

02:39We substitute the phrase sum of numbers with 60. We substitute the phrase number count with 4.

02:46Then, we do the division. 60 divided by 4 equals 15. The mean for this group is 15. Let's summarize what

02:55we found so far. The mean for group 1 is 15, the mean for group 2 is 16, and the mean for group 3 is 15.

03:03Group 1 and group 3 have the same mean, which is 15. Choice B is correct.

03:09Thanks for your attention.

03:20So

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