Stat 215 Quiz 10

# Stat 215 Quiz 10 - p-value = 2*P(Z> | test stat | = 2...

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Stat 215 Qu Module: Quiz , Exercise: HypTest_mu1_mu2 Question 1 (of 1) Question A researcher is comparing two brands of light bulbs. Based on random samples of 100 each, the first brand has a sample mean of 840 hours and a variance of 5500 and the second brand has a sample mean of 800 hours and a variance of 4500. Are the two brands significantly different? Test at the 0.05 level of significance. Answer 1. Null Hypothesis: Mu-x minus Mu-y = 0 2. Alternate Hypothesis: Mu-x minus Mu-y is not equal to 0. 3. Significance level: alpha = 0.05 4. Test Statistic (large sample case): Z = (840 - 800)/sqrt(5500/100 + 4500/100) = 40/10 = 4 5. P-value method:
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Unformatted text preview: p-value = 2*P(Z> | test stat. |) = 2* p(Z> 4) < 2 * 0.0010 < 0.0020 Classical Method : Critical value = 1.96 6. Decision p-value method: Reject Ho if p-value < alpha. Since p-value < 0.05 we reject Ho. Classical Method: Reject Ho if |Z| > critical value. Since | 4 | > 1.96 we Reject Ho 7. Conclusion: At the 5% significance level, we conclude that the two brands of light bulbs have significantly different mean lifetimes. Your Answer Rejection = (1.645,INF) T = 2.31 which is inside the rejection region so the values are significaly different. Grader Comments (none) Grade 4.0 (out of 10.0) Total 4.0 (out of 10.0)...
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## This note was uploaded on 04/03/2008 for the course STAT 215 taught by Professor Dr. during the Spring '08 term at WVU.

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