Situation A. A developer of virtualreality (VR) teaching tool for people who are deaf wants to compare the effectiveness of different navigation methods. A total of 30 children are available for the experiment, of which equal numbers were randomly assigned to use a joystick, wand or gesturebased pinch gloves. The time (in seconds) to complete a designed VR path is recorded for eachchild.

Situation B. A waiter designed a study to see the effects of his behaviors on the tip amounts that he received. For some customers, he would tell a joke; for others, he would describe two of the food items as being particularly good that night; for others, he would check on the table every 10 minutes; and for others, he would behave normally. Using a table of random numbers, he assigned equal numbers of his next 28 customers to his differentbehaviors.

Situation C. A supermarket wants to compare the effects on overall sales of providing free samples of food. An experiment will be conducted from 5:00 p.m. to 6:00 p.m. for the next 20 weekdays. On each day, customers will be offered one of the following when they enter the store: a small cube of cheese pierced by a toothpick, a soft iced cookie, a cracker with choice of hummus spread, ornothing.

For situation A: state the degrees of freedom for the numerator and the degrees of freedom for the denominator of the statistic. dfnumerator=

dfdenominator=