Answer:
C
Step-by-step explanation:
If you have a Ti-84 series calculator, press "stat" then "Edit..." and then fill in the data table values for x and y in two lists. Then press "2nd" and "mode" to quit. Now press "stat" again and right arrow over to "calc" and press down until you find "ExpReg" and set the "Xlist" and "Ylist" that you used and you will get C as the answer. Another way to do this is to manually substitute values into all 4 equations, which is boring.
Answer:
21
Step-by-step explanation:
Using<em> Simple Random Sampling</em>, we can estimate the sample size by the formula
where
n = sample size
Z = the z-score corresponding to the confidence level 99.5%
S = the assumed standard deviation = 3 seconds
e = margin of error = 2 seconds
<em>It is worth noticing that the higher the confidence level, the larger the sample should be.
</em>
The z-score corresponding to a confidence level of 99.5% can be obtained either with a table or the computer and equals
Z = 3.023
Replacing the values in our formula
So the size of the sample should be at least 21.