17) Michele wishes to give a confidence interval for the percentage of Illinois
residents who agree with a certain law. She questions 1500 people from a good
sample and and that 960 agree with the policy. If she chooses a confidence level of
.91, what should her interval estimate for the percentage of people who agree with
this law be? (You may assume that the population of Illinois is infinite.)
A:
I calculated the mean to be .64
The estimated population standard deviation to be .48
The standard deviation to be .4804
When I plug all that in to the formula to get the standard error formula, I get the wrong answer. The teacher says the outcome should be between .61 and .66
18)
(a) What interval estimate for a population parameter M can one get for a confidence interval of .80? (Express the interval in terms of x (the sample mean) and ox (standard error of the sampling distribution.))
A:
I divided 80/2 = 40 which gives a Z value = 1.7
That is all I know for that one.