What is the first error he made in computing the standard deviation?

a. yuri failed to find the difference between each data point and the mean.

b. yuri divided by n instead of n -1.

c. yuri did not subtract 9 - 14 correctly.

d. yuri failed to square -2 correctly.

Step-by-step explanation:

Given is a sample with 4 items as

12,9,14,21

Mean = average of 4 = 14

s is the square root of sample variance

Sample variance is the sum of squares divided by n-1

But Yuri divided by 4 = n instead of 3 = n-1

That is the only mistake he did and all other steps are right.

150

step-by-step explanation:

(sorry i'm not typing it again just read the other two explanation sections i just typed it'll be the same.)