SOLUTION: During a period of 11 years, of 1800 that were selected for grand jury duty, 25% of them were immigrants. Construct a 99% confidence interval for the percentage of grand jury
Algebra.Com
Question 1149653: During a period of 11 years, of 1800 that were selected for grand jury duty, 25% of them were immigrants. Construct a 99% confidence interval for the percentage of grand jury members who were immigrants.
Answer by jim_thompson5910(35256) (Show Source): You can put this solution on YOUR website!
Given information
The value "11 years" is not used at all.
phat = 0.25 is the sample proportion
n = 1800 is the sample size
At 99% confidence, the critical z value is approximately z = 2.576
I used this table to find the critical z value. A similar table should be found in the appendix section of your textbook.
If you choose to use the table I have linked, then locate the bottom row that shows "99% confidence level". Afterward look just above that to find 2.576
Alternatively you can use the invNorm function on your TI83 or TI84 calculator to get the same approximate value.
--------------------------------------
Lets compute the lower bound (L) and the upper bound (U) of the confidence interval.
L = lower bound of confidence interval
L = phat - z*sqrt(phat*(1-phat)/n)
L = 0.25 - 2.576*sqrt(0.25*(1-0.25)/1800)
L = 0.22370881009412
L = 0.22
U = upper bound of confidence interval
U = phat + z*sqrt(phat*(1-phat)/n)
U = 0.25 + 2.576*sqrt(0.25*(1-0.25)/1800)
U = 0.27629118990588
U = 0.28
--------------------------------------
The 99% confidence interval is (0.22, 0.28)
This means at 99% confidence we can say 0.22 < p < 0.28, where p is the population proportion of immigrants selected for grand jury duty.
This is over the time span of the 11 years mentioned.
RELATED QUESTIONS
During a period of 11 years, of 700 people that were selected for grand... (answered by stanbon)
During a period of 11 years 1908 of the people selected for grand jury duty were... (answered by Boreal)
5. in a particular calendar year 10 percent of the registered voters get called for for... (answered by jorel555)
In orange county, 12% of those eligible for jury duty are left-handed. Among 250 people... (answered by stanbon)
60% of all people are eligible for jury duty and favor capital punishment. A jury of 12... (answered by stanbon)
In a small county, there are 140 people on any given day who are eligible for jury duty.... (answered by ikleyn)
Here is my question (I have searched the textbook, tried every potential formula yet I am (answered by zach222)
In 1950, there were 2247,982 immigrants admitted to a country. In 2001, the (answered by josmiceli)
Suppose 60% of all people who are eligible for jury duty in a large Florida city are in... (answered by edjones)