Answer:
The variance is 
Step-by-step explanation:
From the question we are told that
The sample size is n = 21
The sum of squares is 
Generally the variance is mathematically represented as

substituting values


The question ask to find the angle between the given vector to the nearest tenth of a degree and base on the value or the coordinates of each vector, the possible value of the angle base on the said vectors is 1.8 degree. I hope you are satisfied with my answer and feel free to ask for more
This can be solve by using the formula
D = P( 1 – i)^n
Where d is the depreciation value after n years
P is the initial value
i is the depreciation rate
n is the years
D = 1/3 ( 1800)
D = 600
So
600 = 1800 ( 1- 0.45)^n
Solve for n
<span>N = 1.83 years</span>