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:
27 + 28 + 29 = 84
Step-by-step explanation:
x + (x+1) + (x+2) = 84
3x + 3 = 84
84 - 3 = 81
81 / 3 = 27
Answer:
x=2
Step-by-step explanation:
3(5x+2)=8x+20
Distribute the 3
15x +6 = 8x+20
Subtract 8x from each side
15x-8x +6 = 8x-8x+20
7x+6 = 20
Subtract 6 from each side
7x+6-6=20-6
7x=14
Divide each side by 7
7x/7 = 14/7
x=2
I think that you would divide 6x by 2x so C. maybe
I hope this is right