In a survey, a random sample of teenagers were asked whether they have a sibling. The resulting confidence interval for the proportion of teenagers who have a sibling is (0.61,0.91). What is the sample proportion, p^?

And using the property of  symmetry for the confidence interval we can estimate the sample proportion with this formula:

The final answer for this case would be:

So approximately 15% of teenagers have a sibling.

Step-by-step explanation:

For this case we assume that the proportion of interest is who represent the number of teenagers who have a sibling and in order to estimate this proportion we can conduct a confidence interval.

The confidence interval for the mean is given by the following formula:  

And for this case the confidence interval is given by:

And using the property of  symmetry for the confidence interval we can estimate the sample proportion with this formula:

The final answer for this case would be:

So approximately 15% of teenagers have a sibling.

c.

step-by-step explanation:

because first you have to add the 4x, 9x, and the 7x together and you get 20x and then you add the last numbers up and you get 5and then you put the subtraction sign in there and that's how you get the answer.