Answer: The standard deviation formula may look confusing, but it will make sense after we break it down. ...
Step 1: Find the mean.
Step 2: For each data point, find the square of its distance to the mean.
Step 3: Sum the values from Step 2.
Step 4: Divide by the number of data points.
Step 5: Take the square root.
Step-by-step explanation:
Answer:
142.96 dollars
Step-by-step explanation:
80% decrease. because 1% of 300 is 3 which you multiply 3*20 and which means 20 percent equals $60 the leftover percent is the decrease
Using the z-distribution, as we have the standard deviation for the population, it is found that the smallest sample size required to obtain the desired margin of error is of 77.
<h3>What is a z-distribution confidence interval?</h3>
The confidence interval is:

In which:
is the sample mean.
is the standard deviation for the population.
The margin of error is given by:

In this problem, we have that the parameters are given as follows:
.
Hence, solving for n, we find the sample size.






Rounding up, the smallest sample size required to obtain the desired margin of error is of 77.
More can be learned about the z-distribution at brainly.com/question/25890103
Where did you get that A and B? I could answer if you were much more precise.