At child’s 11th birthday party, eight kids were timed to see…

At child’s 11th birthday party, eight kids were timed to see how long (in seconds) they could hold their breath in a relaxed position (event 1). After a two-minute rest, they timed themselves while jumping (event 2). The kids thought that the mean difference between their jumping and relaxed times would be zero. What are the null and alternative hypotheses for testing this claim? (Use the underscore for a subscript: H_o, use a u for mu, and use =\= for not equal to.)