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
00:32the video on how to calculate the average, then we suggest that you view it before watching this
00:37video. The list shows the flight speeds in miles per hour of several birds. What is the mean flight
00:43speed of these birds? We define the mean as the answer to a division problem. In everyday language,
00:50we use the word average instead of the word mean. The word mean is used on math tests and in math
00:56books, but has the same idea and formula as the word average. The mean of a set of numbers equals
01:03the sum of those numbers divided by the number count. There are eight numbers in this list,
01:08so the number count for this set is eight. The sum of these items is the total of 72,
01:14plus 68, plus 95, plus 70, plus 80, plus 62, plus 77, plus 68. That sum equals 592.
01:26Here's the formula for the mean. The mean equals the sum of the numbers divided by the number count.
01:32We substitute the phrase sum of numbers with 592. We substitute the phrase number count with 8.
01:40Then we do the division. 592 divided by 8 equals 74. The mean for this list is 74. The mean flight
01:49speed for these birds is 74 miles per hour. Choice C is correct. Thanks for your attention.
