Answer:
A sample of 179 is needed.
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 Ztable as such z has a pvalue of 
.
That is z with a pvalue of 
, so Z = 1.44.
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.
A previous study found that for an average family the variance is 1.69 gallon?
This means that 
If they are using a 85% level of confidence, how large of a sample is required to estimate the mean usage of water?
A sample of n is needed, and n is found for M = 0.14. So
Rounding up
A sample of 179 is needed.
You can break 98 into 2 49's. Hopefully, we know that 49 is 7 * 7, so 98 is 7 * 14. The correct answer is 14. :)
Answer:
If you are looking for x your answer will be x=2
I'm going to use the substitution method.
4x + 4y = -16
-8x - 6y = -20
4x + 4y = -16
- 4x - 4x
--------------------------
4y = -4x - 16
------ ------ ------
4 4 4
y = -x - 4
-8x - 6(-x - 4) = -20
-8x + 6x + 24 = -20
-2x + 24 = -20
- 24 - 24
----------------------------
-2x = 44
------- -------
2 2
x = 22
4(22) + 4y = -16
88 + 4y = -16
- 88 - 88
------------------------
4y = -104
------ ---------
4 4
y = -26
The answer is (22, -26).
