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


Answer:
7 + 42i.
Step-by-step explanation:
u v = 7i(6 - i)
= 42i - 7i^2 But i^2 = -1 so:
= 42i - 7(-1)
= 7 + 42i.
Answer:
<4 = 22
Step-by-step explanation:
<4 = x
x + 158 = 180
x = 22