483 exploring the web bad weather, bad tips? as part of the study of tip- ping in a restaurant that we met in example 16.3 (page 381) the psychologists also studied the size of the tip in a restaurant when a message indicating that the next day's weather would be bad was written on the bill. here are tips from 20 patrons, measured in percent of the total bill: .35 tip3 19.1 19.2 18.8 18.4 19.0 18.5 16.1 16.8 14.0 136 17.5 20.0 20.2 18.8 18.0 23.2 18.2 19.4 do the data give convincing evidence that the mean percentage tip for all patrons of this restaurant when their bill contains a message that the next day's weather will be bad is less than 20%? (note that 20% is an often-recommended size for restaurant tips.) 5 t versus z. if you examine table c you will notice that critical values of the t distribution get closer and closer to the corresponding critical val