Mistakes in a Song A random sample of six music students played a short song, and the number of mistakes in music each student made was recorded. After they practiced the song 5 times, the number of mistakes each student made was recorded. The data are shown. At a = 0.05, can it be concluded that there was a decrease in the mean number of mistakes? Assume that all variables are normally or approximately normally distributed. Let u, be the mean before and HD = HI - H2. Student A BCDEF Before 12 14 9 8 8 4 After 11 12 5 7 13 3