Chi square

A manufacturer of phone batteries claims that his batteries' lives are approximately normally distributed with a standard deviation equal to 0.9 years. If a random sample of 10 of these batteries has a standard deviation of 1.2 years. Do you think that the standard deviation is greater than 0.9 years? Use 0.05 level of significance

Result

x=




Step-by-step explanation:

s1=0.9 s2=1.2 n2=10 α=0.05  T=16.919 χ2>16.919  S2=s22=1.22=3625=11125=1.44  χ2=(n21) S2/s12=(101) 1.44/0.92=16 χ2<T x=0



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Dr Math
Answer is NO. These is no reason to doubt, that the standard deviation is 0.9 year

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