We have expression
that renders the system of inequalities,

Which can be simplified to,

So what we get is something greater than -1 and at the same time greater or equal to 5, so the solution is,
.
Hope this helps.
Answer:

If we divide both sides by
we got:

And we can use the normal distribution table or excel to find the probabilites and we got:
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 area of a population, and for this case we know the distribution for X is given by:
Where
and 
We select a a sample of n =4 and since the distribution for X is normal then we know that the distribution for the sample mean
is given by:

And we want to find this probability:

If we divide both sides by
we got:

And we can use the normal distribution table or excel to find the probabilites and we got:

Answer:
x = 15
y = 5
Step-by-step explanation:
x = 15
y = 5
16 or B. Because 128 divided by 8 is 16
17: 900 because 3,000 + 900 + 40 +7 is 3,947 or 3,947-3,000-40-7= 900