1.A very large school system claims that it has a 85% graduation rate. A sample of 900 seniors found that 725 received their high school diploma. Construct a 90% proportion confidence interval based on this data and determine whether the data supports the 85% statement.

Start by using the binomial distribution. = n =

a.What is n?

b.What is ?

c.What is ?

d.What is ?

e.What is p? (Note: p is based on our belief about the population. is based on the sample.)

f.What is ?

g.Let _p = sqrt(). What is _p ?

h.We want to make a 90% confidence interval by using the formula

z = k/_p

Should we use a 1 tail or 2 tail z-score?

i.What value of z corresponds to the desired 90% confidence interval?

j.What is k?

k.Construct the confidence interval

(- k) < p_true < (+ k)

l.Is your confidence intervalconsistent with the belief that 85% of high school students graduate? (yes or no, and explain your answer using your computed confidence interval).