Answer: 1/2
Step-by-step explanation:
We have been given that the standard deviation of a group of 20 scores is 15 and we are asked to find variance.
Since we know variance is square of standard deviation. In order to find out the variance of the given data we have to take the square of 15.

Therefore, our variance is 225.
It's important to know that rigid transformations don't change the size or shape, this means the corresponding angles between the image and preimage are congruent. Due to the reflection transformation, angle C corresponds to angle Z.
<h2>Therefore, the answer is angle Z.</h2>
<h3>
Answer: 6.93</h3>
Work Shown:
Use the pythagorean theorem to find x
a^2 + b^2 = c^2
x^2 + 11^2 = 13^2
x^2 + 121 = 169
x^2 = 169 - 121
x^2 = 48
x = sqrt(48)
x = 6.92820323027551
x = 6.93
A- 998.8×997.7=996502.76
B- 998.84×997.73=996572.6332
C- 998.843×997.731=996576.6252
D - 999×998=997002
So D is the answer