A)
sample mean, xbar = 1014
sample standard deviation, σ = 25
sample size, n = 22
Given CI level is 95%, hence α = 1 - 0.95 = 0.05
α/2 = 0.05/2 = 0.025, Zc = Z(α/2) = 1.96
ME = zc * σ/sqrt(n)
ME = 1.96 * 25/sqrt(22)
ME = 10.45
CI = (xbar - Zc * s/sqrt(n) , xbar + Zc * s/sqrt(n))
CI = (1014 - 1.96 * 25/sqrt(22) , 1014 + 1.96 * 25/sqrt(22))
CI = (1004 , 1024)
B)
Z Value at 95% = 1.64
lower bound = mean - z *(s/sqrt(n))
= 1014 - 1.64 *(25/sqrt(22))
= 1005
= 25 hours. A random sample of 22 bulbs The life in hours of a 75-watt...
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