10 Researchers gave 40 index cards to a waitress at an Italian restaurant in New

Question

10 Researchers gave 40 index cards to a waitress at an Italian restaurant in New Jersey. Before delivering the customer, the waitress randomly selected a card and wrote on the bill he same message that was printed on the index card. bill to each Twenty of the cards had the message the day!" Another 20 cards contained the message "The weather is supposed to be not so good tomorrow. I hope you enjoy the day anyway The weather is supposed to be really good tomorrow. I hope you enjoy !" After the customers left, the waitress recorded the amount of the tip, percent o those receiving the good-weather message f bill, before taxes. Given are the tips for 20.8 | 18.7 | 19.9 | 20.6 21.9 | 23.4 | 22.8 | 24.9 | 22.2 | 20.3 24.9 22.3 27.0 20.5 22.2 24.0 21.2 22.1 22.0 22.7 Given are the tips for the 20 customers who received the bad-weather message. 18.0 19.1/ 132 18.8 18.4 19.0 : 18.5 16. i 16.8 14.0 17.0 13.6 17.5 20.0 20.2 18.8 18.0 23.2 18.2 19.4 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 Crunchlt! Stemplots for both data sets are shown. VScroll Good weather tips Bad weather tips Question Source: Moore, The Basic Practice Of Statistics, Be Publisher: W.H Fre

Explanation / Answer

Two-Sample T-Test and CI: good weather, bad weather

Two-sample T for good weather vs bad weather

N Mean StDev SE Mean
good weather 20 22.22 1.95 0.44
bad weather 20 18.19 2.10 0.47

Difference = ? (good weather) - ? (bad weather)
Estimate for difference: 4.030
95% CI for difference: (2.729, 5.331)
T-Test of difference = 0 (vs ?): T-Value = 6.27 P-Value = 0.000 DF = 37

pvalue = 0.000 < alpha = 0.05

Reject null hypothesis.

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