Answer:

And we can find this probability using the normal standard table or excel and we got:

The figure shows the calculation for this case.
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 hardness of a population, and for this case we know the distribution for X is given by:
Where
and 
We are interested on this probability

And the best way to solve this problem is using the normal standard distribution and the z score given by:

If we apply this formula to our probability we got this:

And we can find this probability using the normal standard table or excel and we got:

The figure shows the calculation for this case.
Answer:
D. 89°
Step-by-step explanation:
On the line segment "C," 89 degrees is shown in one corner. x is directly across from it, therefore being the same degrees
Answer:
Equation of a line, y = mx+c
Slope (m)= (Y2-Y1)/(X2-X1), let Y2=7, Y1=3 , X2=2 and X1=1
m=(7-3)/(2-1)
= 4/1
= 4
Picking any value of y and its corresponding x including m, put them into the equation of the line
y=mx+c
3 =4(1)+c
3=4+c
3-4=c
-1=c
y=mx+c
y=4x+(-1)
y=4x-1
Answer:
12.5
Step-by-step explanation:
All I really did was divide the circumference by pi to get the diameter which you end up dividing it by two to get the radius.
Answer:
24
Step-by-step explanation:
m=8x4 n=3x4 so that is the answer