What is the coefficient of a plain
variable such as x or a?

1

0

1

Step-by-step explanation:

If it was 0, then the variable would not be there since anything times 0 is 0. Now you might be wondering how it is 1. Anything times 1 is itself, so there is no need to write x as 1x, you can just write it as x. Same thing with a. No need to write 1a, just a

yes. we do proportions in probabilities.

answer: .64

step-by-step explanation

set up the formula for standard deviation for this set of numbers, then simplify