At one ACT test location students taking the test for a second time volunteered to inhale supplemental oxygen for 5 minutes before the test. In fact, some received oxygen, but others (randomly assigned) were given just normal air. Test results showed that 42 of 66 students who breathed oxygen improved their ACT scores, compared to only 35 of 63 students who did not get the oxygen.
A) Which procedure should we use to see if there is evidence that breathing extra oxygen can help test-takers think more clearly?

Aprofessional hockey team has noticed that, over the past several seasons, as the number of wins increases, the total number of hot dogs sold at the concession stands increases. the hockey team concludes that winning makes people crave hot dogs. what is wrong with the hockey team's conclusion? a) it does not take into account the attendance during each season. b) it does not take into account the number of hamburgers sold during each season. c) it does not take into account the number of concession stands in the hockey arena. d) it does not take into account the number of seasons the hockey team has been in existence.