B if you need an explanation just comment
Answer:
B
Step-by-step explanation:
Standard deviation is the average distance away from the mean, thus B is correct
Answer:
length=4
width=30
Step-by-step explanation:
length=x
width=8x-2
(8x-2)*2+2x=68
16x-4+2x=68
18x=72
x=4 (Length)
4*8=32, 32-2=30(width)
Given:
Polynomials
To find:
Monomial of 2nd degree with leading coefficient 3
Solution:
Monomial is an algebraic expression with only one term.
Option A: 
It is not a monomial because it have 2 terms.
It is not true.
Option B:
It is not a monomial because it have 2 terms.
It is not true.
Option C: 
It have one term only. So, it is a monomial.
Degree means highest power. So degree = 2
Leading coefficient means the value before variable.
Leading coefficient = 3
It is true.
Option D: 
It have one term only. So, it is a monomial.
Degree means highest power. So degree = 3
It is not true.
Therefore
is a monomial of 2nd degree with a leading coefficient of 3.
None of the statements on that list is true.