Can pleasant aromas help a student learn better? Hirsch and Johnston, of the Smell & Taste Treatment and Research Foundation, Chicago, asked subjects to work through a set of two pencil and paper...

Can pleasant aromas help a student learn better? Hirsch and Johnston, of the Smell & Taste Treatment and Research Foundation, Chicago, asked subjects to work through a set of two pencil and paper mazes six times; three times while wearing a floral-scented mask and three times with an unscented mask. Testers measured the length of time it took subjects to complete each of the six trials. The improvement in completion times, expressed as the percentage change in speed of completion from the first trial to the third trial for each maze, was recorded. (Negative values indicate no improvement with completion times longer for the third trial.) The data are attached.

The researchers wanted to determine whether there was more of an improvement in completion times, on average, when wearing a floral-scented mask.

(a)  Clearly indicate why a paired t-test should be used in this analysis.

(b)  What would be the appropriate hypotheses for this test? Explain any symbols used.

(c)  Produce the appropriate t-test output using Excel (with α = 0.05).

Extracted text: ScentTest % Unscented % Scented 33.07 43.13 9.31 -3.66 28.41 42.86 15.26 30.65 21.86 16.42 7.37 16.37 20.44 3.17 -23.43 27.06 -3.35 27.25 32.78 -0.17 22.77 37.3 -6.77 35.89 19.64 22.14 28.69 7.85 9.05 -19.08 11.06 43.12 17.48 29.16 -10.23 -26.72 15.43 38.52 -22.51 12.44 -4.62 26.04