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HW 9 Chap 7 Exemplar

# HW 9 Chap 7 Exemplar - Exemplar for the Homework Problems...

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Exemplar for the Homework Problems from Chapter 7 Required for Homework #9 24. a. Show the sampling distribution of xbar (all values in dollars). 1. ( ) 4260 E x = 2. / 900/ 50 127.28 x n σ σ = = = 3. The sampling distribution of the sample mean is normal by CLT by CLT ( n = 50 > 30) b. Within ±\$250 of μ Want Prob ( μ – \$250 ≤ xbar ≤ μ +\$250) = Prob (4010 x 4510) 4510 4260 1.96 127.28 z - = = Prob (4010 x 4510) = Prob (-1.96 z 1.96) = Prob (z 1.96) – Prob (z -1.96) = 0.9750 – 0.0250 = 0.9500 c. Within ±\$100 Want Prob ( μ – \$100 ≤ xbar ≤ μ +\$100) = Prob (4160 x 4360) 4360 4260 .79 127.28 z - = = Prob (4160 x 4360) = Prob (-0.79 z 0.79) = Prob (z 0.79) – Prob (z -0.79) = 0.7852 – 0.2148

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