Stephen is merging onto a highway. The increase in Stephen's speed for the first 8 8 seconds can be described by the function ()=2+13 f(t)=t2+13t, where t is time in seconds. Which is the average rate of change of () between t=2 and t=6

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.