20. the sample mean is an unbiased estimator for the population mean. this means: (a) the sample mean always equals the population mean. (b) the average sample mean, over all possible samples, equals the population mean. (c) the sample mean is always very close to the population mean. (d) the sample mean will only vary a little from the population mean. (e) the sample mean has a normal distribution.

The answer is option b

Step-by-step explanation:

The point estimator is an unbiased estimator if its expected value is equal to the parameter that it is estimating.

In the case of the sample mean; For all possible observations of X, the expected value of the sample mean will be equal to the population mean.

option c

hope it helps

Step-by-step explanation:

1.4

2.3

step-by-step explanation:

the formula for the constant of variation is

y= kx

divide each side by x

y/x =kx/x

y/x =k

we know a and y

1.   y/x = k

4/1 =4

check the other values to make sure they are the same

8/2 = 4   12/3 =4   and 16/4 =4  

the constant of variation is 4

2.   y/x = k

3/1 =3

check the other values to make sure they are the same

6/2 = 3   9/3 =3   and 12/4 =3  

the constant of variation is 3

6 cm

step-by-step explanation: