Critical value approach: The rejection region, with
α
= 0
.
01 , is
t >
2
.
977 Since the observed value of
t does not fall in the rejection region or
t
0
= 1
.
66
<
2
.
977,
H
0
is not rejected.
There is no sufficient evidence to indicate that the average diameter of the pipes
must not differ significantly from 2.52 mm.
•
Note, you only need give one approach: P-value approach or Critical value
approach.
c G.Li
Page 11 of 22

##### We have textbook solutions for you!

**The document you are viewing contains questions related to this textbook.**

**The document you are viewing contains questions related to this textbook.**

Expert Verified

By G. Li, Don’t Redistributed
STAT 3502 B
Review
Apr 2016
Question
11.
A particular model of HD LCD television has a warranty period of 12 months and
it has a lifetime (before repairs are needed or before it has to be replaced) that is normally
distributed with a mean of 26 months and a standard deviation of 8 months.
(1) What is the probability that this brand of television that you just purchased will not need
repairs during the warranty period?
(2) What is the probability that this television will not need repairs during the first 24 months?
(3) If a one-year extended warranty was offered to you at the time of purchase (i.e., the warranty
period is extended to 24 months) and you purchased it, what is the probability that youmade a wise decision (assuming the cost of repairs or replacement exceeded the cost of theadditional warranty)?
(4) If you did not purchase the extended warranty initially but could purchase it and did
purchase it when your initial warranty expired, what is the probability that you madea wise decision (again assuming the cost of repairs or replacement exceeded the cost ofthe additional warranty)?Should this warranty cost more than if you had purchased itinitially? Explain.
(5) What would the length of the initial warranty period have to be so that only 1 percent of
the televisions would have to be repaired or replaced under warranty?
(6) If the warranty period remains at 12 months and if the mean lifetime can be changed by
using better quality components, what would the mean lifetime have to change to so thatonly 1 percent of the televisions would have to be repaired or replaced under warranty?
(7) If the standard deviation in lifetimes can be changed by using better quality controls, what
would the standard deviation in lifetimes have to change to so that only 1 percent of thetelevisions would have to be repaired or replaced under warranty?
(8) Suppose a gym buys 12 of these televisions for its entertainment area.
Based on theinformation given at the beginning of the question, what is the probability that at leastone of these televisions will need repairs under the warranty period?