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Question 5 of 9 > People tend to be more generous after receiving good news. Are they less generous after receiving bad news? The average tip left by adult Americans is 21%. Give 20 patrons of a restaurant a message on their bill warning them that tomorrow's weather will be bad and record the percentage tip they leave. Given are the tips as a percentage of the total bill. 18 19.1 19.2 18.8 18.4 19 18.5 16.1 16.8 18.2 14 17 13.6 17.5 20 20.2 18.8 18 23.2 19.4 Suppose that percentage tips are Normal with o = 1.8. To access the complete data set, click the link for your preferred software format: Excel Minitab JMP SPSS TI R Mac-TXT PC-TXT CSV CrunchIt! STATE: Is there good evidence that the mean percentage tip is less than 21% ? PLAN: Let u be the average tip percentage for all customers receiving bad news. Choose the correct hypotheses to test. Ho: u = 21 versus Hau # 21 Ho: u = 21 versus Ha: u < 21 Hou < 21 versus Hau > 21 Hou #21 versus Hau > 21 SOLVE: We have a random sample of n = 20 customers and were told to assume tips have a Normal distribution. Find x. (Enter your answer rounded to two decimal places.) x=

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Answer 1

Given х Claim < 21 18.19 1.8 o n 20 Test hypothesis are HO: H: ! 21 21 -u -6.9815011 -6.98 Test statistic za o/ vn p-value =P(z <20) 0.0000 NORMSDIST(z) (Uisng excel) Since p-value is nearly equal to zero hence reject the null hypothesis

Answers are Test hypothesis are Ho: u = 21 H2u<21 363.8 Sample mean i = = 18.19 n 20 Test statistic z=-6.98 P - Value=0.000 Option c is correct