Using the z-distribution, as we are working with a proportion, it is found that the 99% confidence interval for the proportion of all U. S. Adults who would include the 9/11 attacks on their list of 10 historic events is (0.7458, 0.7942). It means that we are 99% sure that the true proportion for all U.S. adults is between these two bounds.
<h3>What is a confidence interval of proportions?</h3>
A confidence interval of proportions is given by:

In which:
is the sample proportion.
In this problem, the parameters are:

The lower limit of this interval is:

The upper limit of this interval is:

The 99% confidence interval for the proportion of all U. S. Adults who would include the 9/11 attacks on their list of 10 historic events is (0.7458, 0.7942). It means that we are 99% sure that the true proportion for all U.S. adults is between these two bounds.
More can be learned about the z-distribution at brainly.com/question/25890103
Answer:
6, 36, 60 have to be multiplied by six in order to get the answer.
Step-by-step explanation:
-2x-y=3 ...(1)
x+2y=4 ...(2)
multiply (2) by 2 and add to (1)
-2x-y+2x+4y=3+8
3y=11
y=11/3
from (2)
x=4-2y=4-2(11/3)
or x=4-(22/3)
=(12-22)/3=-10/3