Answer:
Let X the random variable that represent the heights of a population, and for this case we know the distribution for X is given by:
Where
and
Since the distribution for X is normal then the we know that the distribution for the sample mean
is given by:
And the standard error is given by:

Step-by-step explanation:
Previous concepts
Normal distribution, is a "probability distribution that is symmetric about the mean, showing that data near the mean are more frequent in occurrence than data far from the mean".
The Z-score is "a numerical measurement used in statistics of a value's relationship to the mean (average) of a group of values, measured in terms of standard deviations from the mean".
Solution to the problem
Let X the random variable that represent the heights of a population, and for this case we know the distribution for X is given by:
Where
and
Since the distribution for X is normal then the we know that the distribution for the sample mean
is given by:
And the standard error is given by:

Answer:
I think its the second one, im not quite sure.
Answer:
10 %
Step-by-step explanation:
We first find change in the quantities
Then we write the change in quantity on original quantity and multiply by 100%
This implies that,



Therefore the percentage increase is 10%
Answer:
A
Step-by-step explanation:
I did it in a on a piece of paper
Y²(9y² + 4y - 9)
Simplify.
(y² · 9y²) + (y² · 4y) + (y² · -9)
Simplify.
9y⁴ + 4y³ - 9y²
~Hope I helped!~