Unformatted text preview: n x z= Step 3 Since the H A here is of the “notequalto” type, the test is twotailed. Each tail has a probability equal to a /2. Using a z table we find the critical value to be 1.645. The Decision Rule is “Reject H if the observed z value is more extreme than the critical z value”. Step 4 The calculated value is: 100 5 . 42 400 411 *= z = (411 – 400) / (42.5 / SQRT(100)) = 2.59. Step 5 Conclusion: Reject the null hypothesis H since 2.59 > 1.645, i.e., the calculated value is more extreme than the critical value(s). Therefore, the average lifetime of a light bulb is not equal to 400. a /2 – z cr a /2 z cr 0.05 –1.645 0.05 1.645 – z cr z cr z * = 2.59...
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 Spring '08
 Dr.Jay
 Normal Distribution, Standard Deviation, St. Deviation, Dr. Nick Evangelopoulos

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