Alisha's grandmother has an exercise capacity of 21 minutes, as measured in a similar study among Americans over seventy years old. The study sample has a mean of 16.8 minutes and a standard deviation of 3.9 minutes. Convert Alisha's grandmother's score to a z score among the distribution of exercise capacity in Americans over seventy years old. Who has a relatively longer exercise capacity compared to her peers-Alisha or her grandmother?