During track practice, Yi finished the 100-meter dash with times of 16.2 seconds, 16.6 seconds, and 15.6 seconds. She ran one more time before the end of track practice and finished in 15.6 seconds. What is the mean absolute deviation of Yi's times? A. 0.4 seconds
B. 0.53 seconds
C. 1.6 seconds
D. 0.2 seconds

Arandom sample of n = 25 observations is taken from a n(µ, σ ) population. a 95% confidence interval for µ was calculated to be (42.16, 57.84). the researcher feels that this interval is too wide. you want to reduce the interval to a width at most 12 units. a) for a confidence level of 95%, calculate the smallest sample size needed. b) for a sample size fixed at n = 25, calculate the largest confidence level 100(1 − α)% needed.