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Unformatted text preview: f
σ/ n ≥ zα
2 where x is the sample mean, µ0 is the true value of µ and α is the level of signiﬁcance.
1. 225 ﬂight records are randomly selected, giving a sample mean of 11.6 unoccupied seats. Given that the population
standard deviation of unoccupied seats in a ﬂight is σ = 4.1 seats, estimate a 95% conﬁdence interval for the
2. A company wants to estimate the 99% conﬁdence interval for the lifetime of inkjet printer heads produced. The
lifetime of an inkjet printer head (in millions of characters printe...
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