Sandra wants to evaluate 2 cot Her work is shown below. What did she do wrong?
1 answer:
Answer: The first option.
Step-by-step explanation:
1. To solve this exercise you need to remember that:
- An even function is a function with the following property:
f(-x)=f(x)
- An odd function is a function with this property:
f(-x)=-f(x)
2. By definition, the contangent is an odd function, therefore you have that:
cot(-θ)=-cot(θ)
Then:
3. So, you can coclude that the first step is wrong. Therefore, the answer is the first option.
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Answer:
The new sample size required in order to have the same confidence 95% and reduce the margin of erro to $60 is:
n=28
Step-by-step explanation:
The margin of error is the range of values below and above the sample statistic in a confidence interval.
Normal distribution, is a "probability distribution that is symmetric about the mean, showing that data near the mean are more frequent in occurrence than data far from the mean".
Assuming the X follows a normal distribution
And the distribution for is:
We know that the margin of error for a confidence interval is given by:
(1)
The next step would be find the value of ,
and
Using the normal standard table, excel or a calculator we see that:
If we solve for n from formula (1) we got:
And we have everything to replace into the formula:
And this value agrees with the sample size given.
For the case of the problem we ar einterested on Me= $60, and we need to find the new sample size required to mantain the confidence level at 95%. We know that n is given by this formula:
And now we can replace the new value of Me and see what we got, like this:
And if we round up the answer we see that the value of n to ensure the margin of error required $ is n=28.