## ← 18-13 Summarize_2_Solution

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18-13 Summarize_2_Solution

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Showing Revision 2 created 11/02/2015 by Udacity Robot.

1. The mean is obviously 25.
2. In fact, every element over here is 5 times as large as any element over here.
3. Now, how does this affect the variance?
4. Well, when we compute the differences from the mean, they're going to be 5 times as large.
5. When we square them, they will be 25 times as large.
6. As a result, the variance is 25 times as large as over here--it's 50.
7. And we can quickly check this.
8. Obviously, there is no difference for 25 in the middle.
9. 20 and 25 are 5 apart--the square of this is 25.
10. Same for 30. 15 and 25 are 10 apart. The square is 100.
11. We add those up--we get 250--and now we divide by 5 to get back our 50.
12. The standard deviation is 7.071,
13. and that's exactly 5 times as large as the standard deviation over here.
14. If this is 25 times as large as this one,
15. then the square root of it will be just 5 times as large as this one.
16. You can easily verify that this is the square root of 50.