According to Nielsen//NetRatings, the average visitor to the American Greetings Website spends 11.85 minutes at the site. Assuming this finding to be based on a random sample of 20 visitors to the site, a POPULATION standard deviation of 3.0 minutes, and a population of visiting times that is approximately normally distributed, a 99% confidence interval for the population mean is closest to:.

The 99% confidence interval for the population mean is between 10.12 minutes and 13.58 minutes.

Step-by-step explanation:

We have that to find our level, that is the subtraction of 1 by the confidence interval divided by 2. So:

Now, we have to find z in the Ztable as such z has a pvalue of .

So it is z with a pvalue of , so

Now, find the margin of error M as such

In which is the standard deviation of the population and n is the size of the sample.

The lower end of the interval is the sample mean subtracted by M. So it is 11.85 - 1.73 = 10.12 minutes

The upper end of the interval is the sample mean added to M. So it is 11.85 + 1.73 = 13.58 minutes

The 99% confidence interval for the population mean is between 10.12 minutes and 13.58 minutes.

answer: option a.

step-by-step explanation:

you know that the quadrilateral opqr ( a four sided figure) is inscribed in circle. this means that all its vertices are on the circle.

then, by definition, the opposite angles of the quadrilateral are supplementary, this means that the sum of their measures is 180 degrees.

you can observe in the figure that the angles ∠opq   and the angle ∠orq   are opposite, therefore:

then, can be used to d to calculate the measure of ∠opq