Answer:$8.60
I put the work into the picture. Hope this helps!
Answer:
k=86
Step-by-step explanation:
The slope of the line is
(or just 2) as it rises by 2 units and runs to the left by 1 unit.
Answer:
See the proof below.
Step-by-step explanation:
For this case we just need to apply properties of expected value. We know that the estimator is given by:

And we want to proof that 
So we can begin with this:

And we can distribute the expected value into the temrs like this:

And we know that the expected value for the estimator of the variance s is
, or in other way
so if we apply this property here we have:

And we know that
so using this we can take common factor like this:

And then we see that the pooled variance is an unbiased estimator for the population variance when we have two population with the same variance.