1/3 is the same as 3/9. To solve this, subtract 3/9 from 7/9.

Your answer is
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:



(a) need to find the number of books, we'll call it "b". then the money (6w) minus the cost of books (17b) equals change left over (w)
6w - 17b = w
6w - w = 17b
5w = 17b
(5/17)w = b
(b) if w = 34
(5/17) *34 = b
10 = b
Answer:
2
Step-by-step explanation:
Replace the number with x, then the equation would be:
7x-4=x+8
7x-x=8+4
6x=12
6x/6=12/6
x=2