A set of solar batteries is used in a research satellite. The satellite can run on only one battery, but it runs best if more than one battery is used. The variance ?2 of lifetimes of these batteries affects the useful lifetime of the satellite before it goes dead. If the variance is too small, all the batteries will tend to die at once. Why? If the variance is too large, the batteries are simply not dependable. Why? Engineers have determined that a variance of = 23 months (squared) is most desirable for these batteries. A random sample of 20 batteries gave a sample variance of 12.8months (squared). Using a 0.05 level of significance, test the claim that ?2 = 23 against the claim that?2 is different from 23.
A set of solar batteries is used in a research satellite. The satellite can run on only one battery, but it runs best if more than one battery is used. The variance ?2 of lifetimes of these batteries affects the useful lifetime of the satellite before it goes dead. If the variance is too small, all the batteries will tend to die at once. Why? If the variance is too large, the batteries are simply not dependable. Why? Engineers have determined that a variance of = 23 months (squared) is most desirable for these batteries. A random sample of 20 batteries gave a sample variance of 12.8months (squared). Using a 0.05 level of significance, test the claim that ?2 = 23 against the claim that?2 is different from 23.
MATLAB: An Introduction with Applications
6th Edition
ISBN:9781119256830
Author:Amos Gilat
Publisher:Amos Gilat
Chapter1: Starting With Matlab
Section: Chapter Questions
Problem 1P
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Question
A set of solar batteries is used in a research
satellite. The satellite can run on only one battery,
but it runs best if more than one battery is used.
The variance ?2 of lifetimes of these batteries
affects the useful lifetime of the satellite before it
goes dead. If the variance is too small, all the
batteries will tend to die at once. Why? If the
variance is too large, the batteries are simply not
dependable. Why? Engineers have determined that
a variance of = 23 months (squared) is most
desirable for these batteries. A random sample
of 20 batteries gave a sample variance of 12.8months
(squared). Using a 0.05 level of significance, test the
claim that ?2 = 23 against the claim that?2 is
different from 23.
Transcribed Image Text:(a) What is the level of significance?
0.05
State the null and alternate hypotheses.
O Ho: o² = 23; H₁: ² > 23
O Ho: 0²>23; H₁: o² = 23
ⒸH: o² = 23; H₁: o² #23
O Ho: o² = 23; H₁:0² < 23
(b) Find the value of the chi-square statistic for the sample. (Round your answer to two decimal places.)
What are the degrees of freedom?
19
What assumptions are you making about the original distribution?
O we assume a exponential population distribution.
• We assume a normal population distribution.
O We assume a binomial population distribution.
O We assume a uniform population distribution.
(c) Find or estimate the P-value of the sample test statistic.
OP-value> 0.100
O 0.050 P-value < 0.100
O 0.025 < P-value < 0.050
O 0.010 < P-value < 0.025
O 0.005< P-value < 0.010
OP-value < 0.005
(d) Based on your answers in parts (a) to (c), will you reject or fail to reject the null hypothesis?
O Since the P-value > a, we fail to reject the null hypothesis.
O Since the P-value > a, we reject the null hypothesis.
O Since the P-value ≤ a, we reject the null hypothesis.
O Since the P-value ≤ a, we fail to reject the null hypothesis.
(e) Interpret your conclusion in the context of the application.
O At the 5% level of significance, there is insufficient evidence to conclude that the variance of battery life is different from 23.
O At the 5% level of significance, there is sufficient evidence to conclude that the variance of battery life is different from 23.
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