A study reported that that orthodontic patients wore their retainers on average 14.78 hours a day with a standard deviation of 5.31. An enterprising orthodontist saw this study and wondered if watching a video on how to wear a retainer would make their patients wear one longer. They randomly selected 15 patients at their clinic and had them watch the video. They found that on average these patients wore their retainers for 17 hours a day. What test should the researcher use to determine whether or not this is a meaningful difference?

a.

Two sample z-test

b.

One sample t-test

c.

Pooled t-test

d.

Two sample t-test

e.

One sample z-test