Answer: its b
Step-by-step explanation:
Variance of a continuous random variable X is defined as
Standard deviation is defined as

Hence standard deviation is the positive square root of variance.
Each position in the sequence has 3 choices, and there are 5 positions, so we multiply 3 by itself 5 times:
Answer:
, where n = 1,2,3,4,.....
Step-by-step explanation:
The given sequence : 1, 8, 27, 64, ….
We observe that the terms are perfect cubes of consecutive integers (starting from 1) .
Terms can be written as:
First term = 
Second term=
Third term = 
Fourth term =
Thus , for any nth term ,the formula for the sequence is :
, where n = 1,2,3,4,.....