Answer:
There are 157.48 inches in 4 meters.
B. False
X and Y are two different variables.
If it is directly proportional, then:
m = kx
10 = k x -4
k = -2.5
m = 3 x -2.5
m= 7.5
Hope I helped!
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.