my answer is in the image above
Answer:
a) A sample size of 5615 is needed.
b) 0.012
Step-by-step explanation:
In a sample with a number n of people surveyed with a probability of a success of
, and a confidence level of
, we have the following confidence interval of proportions.

In which
z is the zscore that has a pvalue of
.
The margin of error is:

99.5% confidence level
So
, z is the value of Z that has a pvalue of
, so
.
(a) Past studies suggest that this proportion will be about 0.2. Find the sample size needed if the margin of the error of the confidence interval is to be about 0.015.
This is n for which M = 0.015.
We have that 






A sample size of 5615 is needed.
(b) Using the sample size above, when the sample is actually contacted, 12% of the sample say they are not satisfied. What is the margin of the error of the confidence interval?
Now
.
We have to find M.



Answer in image.
Knowledge point: Trigonometry - tangent concept
Answer:
y=6x+11
Step-by-step explanation:
Answer: the width of the uniform path is 9 meters.
Step-by-step explanation:
Let x represent the width of the uniform path.
A pool measuring 18 meters by 22 meters is surrounded by a path of uniform width. It means that the combined length of the pool and the uniform path is (18 + 2x) meters and the combined width of the pool and the uniform path is (22 + 2x) meters.
If the area of the pool and the path combined is 1440 square meters, it means that
(18 + 2x)(22 + 2x) = 1440
396 + 36x + 44x + 4x² = 1440
4x² + 80x + 396 - 1440 = 0
4x² + 80x - 1044 = 0
Dividing both sides of the equation by 4, it becomes
x² + 20x - 261 = 0
x² + 29x - 9x - 261 = 0
x(x + 29) - 9(x + 29) = 0
x - 9 = 0 or x + 29 = 0
x = 9 or x = 29
Since the width cannot be negative, then x = 9 meters