Answer:
thanks im not smart
Step-by-step explanation:
sn i knew that...
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:
V = 432pi cm^3
Step-by-step explanation:
Pi x r^2 x h
Pi x 6^2 x 12 cm = 432 pi cm^3
5+5= 10
10 time 9b is 90b
10 times -7 is -70
Then 90b-70
Two quadrilateral rectangles:
1. 6x5= 30
2. 5x10= 50
Two right triangles:
1. 10x6/2= 30
2. 10x6/2= 30
Then you add them all up:
30+50+30+30= 140 sq. units