Answer:
that is hard srry but i cant help on this one.
Step-by-step explanation:
The answer for 4 is 12..
hope it helps u..
have a great day ahead! :)
The mistake he made is that he Yuri divided by n instead of n -1.
<h3>What mistake did he make?
</h3>
Standard deviation is used to determine how the values in a group differs from the mean of the values in the group.
In order to determine the standard deviation, take the following steps:
• Determine the mean of the observation: 14
Determine the difference between each value and the mean and then square the result: (12 - 14)² + (14 - 14)² + (9 - 14)² + (21 - 14)² = 78
Determine the mean of the sum of the squared differences and then find the square root of the mean: √78/(n - 1) = 5.1
To learn more about standard deviation, please check: brainly.com/question/26201837
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You can use side-angle-side postulate
Answer: 19.625 cm (Formula is 2πr)
Steps: 1.) 3.14 * 12.5 = 39.25
2.) 39.25 * 2 = 78.5
3.) 78.5 / 4 = 19.625 (using the 4 because the area is a fourth of a whole circle)