At one SAT test site students taking the test for a second time volunteered to inhale supplemental
Oxygen for 10 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 SAT scores, compared to only 35 of 63 students who did not get the oxygen.
Which procedure should we use to see if there is evidence that breathing extra oxygen can help
Test-takers think more clearly?
A) 2-proportion $z$-test
B) 1 -proportion z-test
C) 1 -sample $t$-test
D) matched pairs $t$-test
E) 2-sample $t$-test

Question

At one SAT test site students taking the test for a second time volunteered to inhale supplemental
Oxygen for 10 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 SAT scores, compared to only 35 of 63 students who did not get the oxygen.
Which procedure should we use to see if there is evidence that breathing extra oxygen can help
Test-takers think more clearly? 
A) 2-proportion $z$-test
B) 1 -proportion z-test
C) 1 -sample $t$-test
D) matched pairs $t$-test
E) 2-sample $t$-test

Quizplus · Accepted Answer

The correct procedure is a 2-proportion z-test because we are comparing the proportions of students who improved their SAT scores in two independent groups: those who breathed oxygen and those who did not.

At One SAT Test Site Students Taking the Test for a Second