31
examples
Example
Suppose 800 students were selected at random from a student body
of 20,000 and given shots to prevent a certain type of flu. All 800
students were exposed to the flu and 600 of them did not get the flu.
Let p present the probability that the shot will be successful for any
single student selected at random from the entire population of
20,000. Let q be the probability that the shot is not successful.
a) What are the point estimates for p and q?
b) Find a 99% confidence interval for p.
Procedure
1
m
STAT2
2
4
(INTR)
b
(Z)
d
(1-Prop)
3 .jj
w
gaa
w
iaa
w
1
(None)
c
4
1
(CALC)
Result Screen
a) The point of estimates for p = 0.75, and the point of
estimates for q = 1-p = 0.25.
b) Thus, the 99% confidence interval for p
becomes 0.71<p<0.79 .
