Dr. humor wonders if knock-knock jokes are funnier than jokes involving “crossing the road.” he has several people tell participants a series of both types of jokes and has the participants rate how funny they believe each joke to be. in this example, the dependent variable is

Katie and her father are looking at the pipes around their house. they find that some of the pipes have rust on them, making them look and feel different than normal pipes. what kind of change have the rusted pipes gone through? a. a physical change b. a vibration change c. a chemical change d. a temperature change