HOMEWORK P.410:  33) ; reject the null hypothesis.  34) ; fail to reject the null hypothesis  35) ; reject the null hypothesis  36) ; reject the null hypothesis  38) There is sufficient evidence to support the claim that the percentage of on-time U.S. airlines flights is less than 75%.  39) There is not sufficient evidence to warrant rejection of the claim that the percentage of Americans who know their credit score is equal to 20%.

Testing a Claim About a Proportion SECTION 8.3

 Medicine:  Are certain medications effective?  Can pregnant women correctly guess the sex of their babies?  Do different medical procedures provide the results they promise?  Entertainment:  How effective are different commercials?  How many people watch the Super Bowl – are these high priced ad spaces worthwhile?  Business  Do products work as advertised?  How many people might be interested in a new product?  Create your own! WHY TEST A CLAIM?

Section 8.2  We looked at the individual components of a hypothesis test and how they each work. Section 8.3  We will test different proportion claims to determine if they are true or not. WHAT’S THE DIFFERENCE?

THE HOW TO

 The XSORT is a method of gender selection that promises couples an increased chance of having a baby girl. Among 726 babies born to couples using the XSORT method in an attempt to have a baby girl, 668 of the babies were girls and the others were boys. Use these results with a 0.05 significance level to test the claim that among babies born to couples using the XSORT method, the proportion of girls is greater than the value of 0.5 expected with no treatment. THE PROBLEM

THE HOW TO

 Step 3: Calculate the appropriate test statistic THE HOW TO

 Step 4: Determine the P-value (Draw a picture) THE HOW TO

 Step 6: State conclusion in simple non-technical terms THE HOW TO

 A study addressed the issue of whether pregnant women can correctly guess the sex of their baby. Among the 104 subjects, 55% correctly guessed the sex of the baby. How many of the 104 made correct guesses? FINDING THE NUMBER OF SUCCESSES X

 If you can create a confidence interval using the sample statistic, and it does not contain the value for the parameter given by the null hypothesis, you can reject the null hypothesis. SIDE NOTE: CONFIDENCE INTERVAL METHOD

 p. 421 #9-12 HOMEWORK