Answer:
a) The minimum sample size is 601.
b) The minimum sample size is 2401.
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:
For this problem, we have that:
We dont know the true proportion, so we use 
, which is when we are are going to need the largest sample size.
95% confidence level
So 
, z is the value of Z that has a pvalue of 
, so 
.
a. If a 95% confidence interval with a margin of error of no more than 0.04 is desired, give a close estimate of the minimum sample size that will guarantee that the desired margin of error is achieved. (Remember to round up any result, if necessary.)
This is n for which M = 0.04. So
Rounding up
The minimum sample size is 601.
b. If a 95% confidence interval with a margin of error of no more than 0.02 is desired, give a close estimate of the minimum sample size necessary to achieve the desired margin of error.
Now we want n for which M = 0.02. So
The minimum sample size is 2401.
When reading a question, you need to be aware of the numbers presented and the facts. You need to pay attention to the question - what, when, where, how, why or how much. What is being asked in the question is always your clue. Unnecessary information will be eliminated once you understand the question.
Simple example from a Business book:
Jessica Fernandez, manager of Subway, had a bank balance of $5382.12 on March 1. During March, she deposited $60,375.82 received from sales, $3280.18 received as credits from suppliers, and $75.53 as a county tax refund. She paid out $27,282.75 to suppliers, $4280.83 for rent and utilities, and $12,252.23 for salaries and miscellaneous. How much did Fernandez deposit in March?
Answer:
$60,375.82 (sales) + $3280.18 (credits) + $75.53 (refund) = $63,731.53
Fernandez deposit $63,731.53 in March.
The question immediately lead you to the sentence that is the key to the answer.
It is pretty obvious but try to recognize the important facts from the rest.
The question did not ask about Jessica's balance on March 1 or did not ask about how much she pay out. You can immediately eliminate that those information are not necessary to the problem being asked. The question is how much did she deposit in March. You need to find the sentence that points out the answer - During March, she deposited $60,375.82 received from sales, $3280.18 received as credits from suppliers, and $75.53 as a county tax refund. List all the numbers and add them together and you will come up with the figures she deposited. It is just a simple question but it presented the technique for the elimination process of unnecessary facts. It is not "we cannot see the answer" but the truth is we cannot see and understand the question.
The answer is x².
f(x) = <span>5x - 6
</span>g(x) = x²<span> - 5x + 6
(f + g)(x) = f(x) + g(x)
= </span>5x - 6 + x² - 5x + 6
= x² + 5x - 5x + 6 - 6
= x² + 0 + 0
= x²
