EC315_PROCTORED_FINAL_EXAM_review

# EC315_PROCTORED_FINAL_EXAM_review - HAT CAN NEVER BE...

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t (df) THAT CAN NEVER BE NEGATIVE OR GREATER THAN ONE IN VALUE. ALWAYS INFINITY ( ) EC315 FINAL EXAM REVIEW PART I. HYPOTHESIS TESTING PROBLEM 1 A certain brand of fluorescent light tube was advertised as having an effective life span before burning out of 4000 hours. A random sample of 84 bulbs was burned out with a mean illumination life span of 1870 hours and with a sample standard deviation of 90 hours. Conduct a one-tail hypotheses test at alpha = .10 to determine if this sample data provides sufficient evidence to indicate that the bulbs have their advertised life expectancy. Do NOT do a confidence interval. PROBLEM 2 Given the following data from two independent data sets, conduct a one-tail hypothesis test to determine if the means are statistically equal using alpha=0.05. Do NOT do a confidence interval.

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n 1 = 35 n 2 = 30 xbar 1 = 32 xbar 2 = 25 s 1 =7 s 2 = 6 Ho: u1 greater/equal u2 H1: u1 < u2 Reject Ho if z < 1.65 z = 32 - 25 7sq + 6sq 35 30 = 1.4 + 1.2 = 2.6 sq root of 2.6 = 1.612 7/1.612 = 4.31 Do not reject Ho 2
PROBLEM 3. A test was conducted to determine whether gender of a display model affected the likelihood that consumers would prefer a new product. A survey of consumers at a trade show which used a female spokesperson determined that 120 of 300 customers preferred the product while 92 of 280 customers preferred the product when it was shown by a male spokesperson. Do the samples provide sufficient evidence to indicate that the gender of the salesperson affect the likelihood of the product being favorably regarded by consumers? Evaluate with a two-tail, alpha =.01 test. Do NOT do a confidence interval. did not reject the null hypothesis because it was not greater than the critical value of 2.576 or less than -2.576. 3

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PROBLEM 4 A suming that the population variances are equal for Male and Female GPA’s, test the following sample data to see if Male and Female PhD candidate GPA’s (Means ) are equal. Conduct a two-tail hypothesis test at α =.01 to determine whether the sample means are different. Do NOT do a confidence interval. Male GPA’s Female GPA’s Sample Size 12 13 Sample Mean 2.8 4.95 Sample Standard Dev .25 .8 Hypothesis Test: Samples Tests Exxon claims their gas gives better gas mileage than Shell's gas. We want to try and prove it. We get 40 drivers, and let 20 use Exxon gas and 20 use Shell gas, each recording their gas mileage. We set up a one-sided hypothesis test in order to prove the claim at the five percent level of significance. The sample data are given as follows: Exxon Shell Sample Mean 25.3 21.4 Sample Variance 15.1 14.8 N 20 20 USE THIS? Step 1:
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EC315_PROCTORED_FINAL_EXAM_review - HAT CAN NEVER BE...

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