Answer:
B. Yuri divided by n instead of n-1
Step-by-step explanation:
It was stated in the question that the dataset was sample dataset. For a sample dataset, the standard deviation is given by the formula,
σ = √ Σ (Xi - mean)²/(n - 1) where i = 1,2,3.....n
Since this is just a sample dataset and not the whole population, Yuri should have divided by n-1 instead of n.
Answer:

Step-by-step explanation:
![\sqrt[3]{-729a^9b^6} =](https://tex.z-dn.net/?f=%5Csqrt%5B3%5D%7B-729a%5E9b%5E6%7D%20%3D)




A direct variation is a mathematical relationship between two variables that can be expressed by an equation in which one variable is equal to a constant times the other. In other words, a direct variation is where

.
In answer a,

, so it is a direct variation.
In answer c,

, so it is a direct variation.
In answer d,

, so it is a direct variation,
Only answer b is left, which means the answer must be 'b'.
We also know 'b' is the answer because it cannot be expressed as <span>

. Instead, it is expressed as </span>

, which is not the same thing and is therefore not a direct variation.
Hope I helped, and let me know if you have any questions :)
A) y= -2, 3, 7
B) y= 8, 0, -6
C) y= -8, 1, 7
d) y= 1, -2, -6