Homework ch 14
Stat 145 -018 KAFB SP 2014
A. From the Text: Problems : 14.4 , 14.16 4.20,
B. Additional exercises:
1. Find the z* for a CI of a) 82% , b) 92%
c) 93%
2. Given 18 newts, whose healing rate is assumed to come from a normal distribution with unknown
mean  , if x was calculated to be 26.67, the standard deviation of the population is assumed to be 8,
then the 90% confidence interval for  is: ???
3.
Which of the following describes a scenario in which the resulting statistical inference is probably
trustworthy?
A) A professor is interested in estimating the average height of all college students at her
college. He uses her large introductory class as a sample of students from the college to construct
a 95% confidence interval for the average height.
B) A mathematics professor is interested in estimating the average number of mathematics
classes taken by students at her college. She uses the students in her mathematics classes to form
a sample of all students at the college. Based on her sample, she constructs a 95% confidence
interval for the average.
C) A quality control inspector periodically inspects parts being manufactured for quality. He
wants to estimate the average diameter of all parts. For a sample, he selects 10 consecutive parts
as they are manufactured. He constructs a 95% confidence interval for the average diameter.