Answer:
n=97
Step-by-step explanation:
1) Notation and definitions
population standard deviation known
Confidence=90% or 0.9
n sample size required (variable of interest)
A confidence interval is "a range of values that’s likely to include a population value with a certain degree of confidence. It is often expressed a % whereby a population means lies between an upper and lower interval".
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".
The sample mean have the following distribution
2) Calculation for the sample size required
In order to find the critical value we need to take in count that we are finding the interval for the mean with the population deviation known, so on this case we need to use the z distribution. Since our interval is at 90% of confidence, our significance level would be given by and . And the critical value would be given by:
The margin of error for the sample mean interval is given by this formula:
(a)
And on this case we have that and we are interested in order to find the value of n, if we solve n from equation (a) we got:
(b)
And replacing into equation (b) the values from part a we got:
And rounded up we have that n=97
5(x2 − 8)
5(x + 8)(x − 5
Prime
Your Answer:
C.) 5(x² - 8)
Step-by-step explanation:
If you were to redistribute the 5 in 5(x² - 8), you would get 5x² - 40, which was what you initially started off with.
Hope this helps y'all :)