Answer:
The minimum sample size needed is
. If n is a decimal number, it is rounded up to the next integer.
is the standard deviation of the population.
Step-by-step explanation:
We have that to find our
level, that is the subtraction of 1 by the confidence interval divided by 2. So:

Now, we have to find z in the Z-table as such z has a p-value of
.
That is z with a pvalue of
, so Z = 1.645.
Now, find the margin of error M as such

In which
is the standard deviation of the population and n is the size of the sample.
How large a sample must she select if she desires to be 90% confident that her estimate is within 4 ounces of the true mean?
A sample of n is needed, and n is found when M = 4. So






The minimum sample size needed is
. If n is a decimal number, it is rounded up to the next integer.
is the standard deviation of the population.
Answer:
the answers to this are x= 1 and y= 9
Steps:
1. Multiply the first line by 3 and the second by 2
3(3x + 2y= 4)
2(8x -3y=-6)
2. New lines are
9x + 6y= 12
16x + -6y=-12
3. Now add/subtract them
25x + 0= 0
25x=0
4. Divide by 25
X=0
5. To find y, substitute the 0 in the x in one of the equations
9x + 6y= 12
9(0) + 6y= 12
6y= 12
6. Divide by 6, your Y=2
7. X=0, Y=2
The answer is (-7r-6s)/3s