Answer:
a)
b) 
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".
Part a
Let X the random variable that represent the weights 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 like this:
And in order to find these probabilities we can find tables for the normal standard distribution, excel or a calculator.
Part b
For this case we select a sample size of n =32. Since the distribution for X is normal then the distribution for the sample mean
is given by:
And the new z score would be:



Answer:
D) y = -1/2x + 4
Step-by-step explanation:
Points on the graph: (0, 4) and (8, 0)
Slope:
m=(y2-y1)/(x2-x1)
m=(0 - 4)/(8-0)
m= -4/8
m = -1/2
Slope-intercept:
y - y1 = m(x - x1)
y - 4 = -1/2(x - 0)
y - 4 = -1/2x
y = -1/2x + 4
Answer:
1
Step-by-step explanation:
You would use B to find X